CETONIA INDA.-This common insect which in former years was a harmless beetle feeding in early spring on the sap of freshly cut maple trees has, within two or three years, become very abundant and destructive in different parts of New England. During the past summer it collected in great numbers on green corn, eating the kernals and partly destroyed a field in Middleboro, Mass., as we learn from Prof. Jenks.—A. S. P.

CAUSE OF THE TWISTING OF Spiral ShellS.-At the end of his essay on the development of the pulmonate Gasteropods, M. Fol inquires into the cause of asymmetry of univalve shells; by most authors it has been ascribed to the folding round of the shell; Ihering, however, regards the torsion of the shell as due to the asymmetry of the viscera. Fol regards both these opinions as too extreme, as in the Heteropoda asymmetrical arrangements manifest themselves at an extremely early period. In Helix and Limax the torsion does not appear so early, and is seen simultaneously in the viscera and in the shell. To explain the phenomena, it seems to be necessary to note the process of segmentation of the ovum; but here unfortunately there is but little information. The fact that organs like the kidneys, which are, as we know, primarily double, are in the youngest of Gasteropod larvæ, single, seems to show that the asymmetry is produced prior to the commencement of the embryonic period. In conclusion, as reported in the Journal of the Royal Microscopical Society, the author points out how recent observations tend to favor the reëstablishment of the Vermes of Linnæus. It is impossible, Fol says, to compare the molluscan larva with a segmented worm larva; they only correspond to the cephalic portion of the larva of an Annelid, or to an entire Rotifer; the Mollusca are not segmented animals which have fused their segments, but they are animals which have remained simple. In the Vermes, on the other hand, the larval form (Lovenian, veliger, trochosphere) can, with variations in form, be traced through "worms," Annelids, Bryozoa, Brachiopods, and even Echinoderms, and these all form. a phylum quite distinct from that of the Arthropoda on the one hand, and of the Chordata (Tunicata and Vertebrata) on the other.

THE YOUNG OF THE CRUSTACEAN LEUCIFER, A NAUPLIUS.-One of the most interesting observations which we have made this summer is, that Leucifer leaves the egg as a Nauplius. As Fritz Müller did not raise the young of Peneus, but relied upon surface collecting, his observations are not absolutely conclusive, but I have seen Leucifer lay its eggs, and I have seen the exit of the Nauplius from the egg, so the occurrence of a Nauplius is proved, absolutely, in one stalk-eyed Crustacean.

As almost nothing was known about the habits of Leucifer, and nothing whatever about its embryology, I have devoted especial

attention to this interesting species this summer, but although the animals are very abundant I have been baffled in all my attempts to find the eggs or young until within the last week, but have now got on to the right track, and can get a complete history if the weather is calm for a week longer.

The animals are remarkably regular in their breeding habits. They copulate late in the afternoon; the eggs are laid about nine o'clock in the evening, and they hatch in about thirty-six hours. The eggs are attached very loosely in an irregular bunch of about twelve or fourteen, to the last pair of thoracic appendages. They fall off at the slightest touch, and this, together with the rapidity. of their development, explains the failure to find them in specimens collected at the surface. As they do not flourish in confinement, the eggs cannot be procured in any quantity from captive specimens, and until their breeding habits were known, the investigation presented great difficulties. By going out about eight o'clock on a calm evening and dipping very carefully with a hand net, a great number of individuals may be procured, and if these are carried home with great care and left undisturbed until about ten o'clock, careful examination will then show that several specimens have bunches of new-laid unsegmented eggs. If these specimens are carefully picked out, and placed by themselves, they can be kept, without much difficulty, until the eggs hatch, on the second morning after the adults were collected.

The course of development is of unusual interest, as Leucifer, like Amphioxus, presents what must be regarded as an unmodified embryonic history. Segmentation is total and perfectly regular, and the cells double their number at each cleavage, even after they have become very small, and many hundreds in number.

There is a true invaginate gastrula, which is as beautifully simple, and unmodified as the well-known gastrula of Sagitta.

The Nauplius is a typical nauplius, very much like that of a barnacle, or that of Cyclops, and is a marked contrast to the peculiar and specialized Nauplius of Penæus. If I had not seen it hatch I should certainly have supposed it to be a Copepod embryo, as the resemblance is perfect.

In this connection I may state that Mr. Wilson has succeeded in raising zoëas from the eggs of Libinia, and of a closely-allied genus. In these, the most highly specialized of the Decapods, the embryonic record is accelerated so much that the zoëa has its full number of thoracic appendages when it leaves the egg, so the embryology of Leucifer is at one end of the series and the embryology of Libinia at the other.

Wilson has also raised the zoëas of the following crabs from the egg, this summer: Porcellana, Pinnixa, Sesarma, Pinnotheres, Callinectes.

The skin which the crab zoëa sheds soon after it leaves the egg has been regarded as a Nauplius skin, but the fact that the Naup

lius of Leucifer leaves the egg encased in a similar skin, and molts it soon after, seems to indicate that it has no morphological significance.-W. K. Brooks, Beaufort, N. C., Sept. 5.

THE FRIGATE MACKEREL, AUXIS ROCHEI, ON THE NEW ENGLAND COAST. The United States Fish Commission has obtained numerous specimens of a fish, before entirely unknown in the Western Atlantic. This is the frigate mackerel, Auxis rochei, twenty-eight barrels of which were taken in a mackerel seine, ten miles east of Block island, on the 3d of August, by the schooner American Eagle, Capt. Josiah Chase, of Provinceton, Mass.

The Frigate mackerel resembles in some particulars the common mackerel, in others the bonito; the genus Auxis being intermediate in its character between the Scomber and the related genera Pelamys and Orcynus. It has the two dorsal fins remote from each other as in Scomber, and the general form of the body is slender, like that of the mackerel. The body is, however, somewhat stouter, and instead of being covered with small scales of uniform size, has a corselet of larger scales under and behind the pectoral fins. Instead of the two small keels upon each side of the tail which are so noticeable in the mackerel, it has the single more prominent keel of the bonito and the tunny. Its color is grayish-blue, something like that of the pollack, the belly being lighter than the back. Under the posterior part of the body, above the lateral line, are a few cloudings or maculations resembling those of the mackerel. The occurrence of a large school of this beautiful species in our waters is very noteworthy, for the fish now for the first time observed are very possibly the precursors of numerous schools yet to follow. It is not many years since the bonito became an inhabitant of our waters, and the distribution and habits of the frigate mackerel are supposed to be very similar to those of the bonito, Sarda pelamys, and the little tunny, Orcynus alliteratus, which also first came on the coast in 1871, and have since been found in considerable numbers.

The frigate mackerel has been observed in the West Indies and other parts of the tropical Atlantic as well as on the coast of Europe. In Great Britain it is called the "plain bonito." It is not unusual in the Bermudas, where it is called the "frigate mackerel," a name not inappropriate for adoption in this country, since its general appearance is more like that of the mackerel than the bonito, while in swiftness and strength it is more like the larger members of this family.

Since the first appearance of this fish many new observations of its abundance have been received. These fish seem to have come in immense schools into the waters between Montauk point and George's bank, and from Mr. Clark's statements it appears that they have been observed in small numbers by fishermen in previous years. Several vessels have come into Newport recently, reporting their presence in immense numbers in the

vicinity of Block island. It will interest the "Ichthyophagists' Club" to know that several persons in Newport have tested the fish, and pronounce it inferior to the bonito. Part of the flesh, that on the posterior part of the body, is white, but behind the gills it is black and rank, while the meat near the backbone is said to be of disagreeable, sour flavor.

It is hard to predict what its influence will be upon other fishes already occupying our waters. Its mouth is small and its teeth feeble, so that it is hardly likely to become a ravager like the bonito and the bluefish. There is little probability, on the other hand, that its advent will be of any special importance from an economical point of view, for its oil does not seem to be very abundant, and it would hardly pay at present to capture it solely for the purpose of using its flesh in the manufacture of fertilizers. Mr. A. Howard Clark, in charge of the Fish Commission' station at Gloucester, has communicated to Prof. Baird some interesting facts regarding its abundance. From these statements it would also appear that the species has been observed occasionally in past years. He writes under date of August 10th: "I have received this morning from the schooner Fitz F. Babson, just arrived from Block island, a fish answering to your description of the Auxis, having a corselet of scales around the pectoral fin as in the tunny. The captain of the vessel, Joshua Riggs, reports that about a week ago he had a hundred barrels in the seine at one time, and saw over twenty schools of them. He saw them as far east as Sow-and-Pig light ship. They are very easy to catch, flip like menhaden, do not rush, and are not frightened at the seine. They go in immense numbers, he thinks, as many as one thousands barrels to a school. The day after the appearance of these fish the mackerel disappeared, but he does not know whether the mackerel were driven away by them or not. They feed on mackerel food. Mr. Daniel Hiltz, of the same vessel, says that he caught one of just the same kind in February, 1879, on a haddock trawl on the eastern part of the Middle Bank in forty fathoms of water. He took it to Boston, where it was called a young bonito."

Mr. John Henderson, of the schooner Sarah C. Wharf, says that two vessels caught such fish recently, eastward of here; the schooner American Eagle, of Provincetown, took a number of barrels of them into Newport, and sold them for a dollar a barrel. Another Cape Cod vessel, he does not know her name, took about fifty barrels of them and threw them away. All the mackerel seiners from Block island report seeing quantities of this new fish within the past fortnight. The captain of the schooner Sarah C. Wharf says he first saw them a fortnight ago some fifteen miles off Block island. The captain and several of the crew of the Ella M. Johnson, of Newburyport, just arrived from Block island, state they saw abundance of the Auxis, but did not know what it was

until reports came from you at Newport. They opened one and found in its stomach the ordinary red mackerel food. This crew differ with the crew of the schooner Fitz. J. Babson with regard to the ease of capturing them-think them rather difficult to take; say they flip like porgies, and do not rush like mackerel ; they saw ten large schools of them on Saturday last when some fifteen miles south of Block island.

I hope that any reader of the AMERICAN NATURALIST who has seen this fish will mention it; some may, perhaps, have an opportunity of studying its habits. The length of those I have seen ranges from twelve to sixteen inches, and their weight from threequarters of a pound to a pound and a-half or more. Those sent to New York market were part of the lot taken by the schooner American Eagle and brought into Newport, whence they were shipped by Mr. Thompson, a fish dealer of this place. It would require from eighty to one hundred of them to fill a barrel, so the estimate of Capt. Riggs that there are a thousand barrels in one of the schools, shows how exceedingly abundant they must be.

Capt. N. E. Atwood, of Provincetown, Mass., the veteran fisherman-ichthyologist, has examined the specimens, and is satisfied that they belong to the same species as fish which he found abundant in the Azores in 1840, when, led by the reports of Cape Cod whalers, he went to these islands in search of mackerel, the mackerel fishing being poor at home. No mackerel were found except the "frigate mackerel " referred to in this note.-G. Brown Goode, Summer Station U. S. Fish Com., Newport, R. I., Aug. 30, 1880.

ON THE OCCURRENCE OF FREIA PRODUCTA WRIGHT, IN THE CHESAPEAKE BAY.-Sometime in 1851 Prof. Leidy called attention to the existence of Freia ampulla in American waters, and from the poor figures of the European form then in existence, he was led to consider it a new species under the name of F. americana, but he now considers both forms the same. As they are amongst the most singular and beautiful of the family of the trumpet animalcules or Stentorina, I take pleasure in announcing that I have found the still more interesting species, F. producta T. S. Wright, in shallow waters on the western shore of the Chesapeake, attached in vast numbers to the shells of oysters, in company with ? Loxosoma and other bryozoa.

The tubes in which the animalcule resides are formed of a narrow transparent ribbon of horny consistency, wound into a spiral and terminating in a trumpet-shaped extremity from which the odd peristome of the inhabitant protrudes. The basal or attached end of the tube is usually bent at an angle to the tube and bears a striking resemblance to the foot end of a stocking fastened to some other object by the surface on which the sole rests. This portion is not composed, like the tube, of a spiral ribbon, but is simply a thin-walled sac, from the open end of which the ribbon