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unknown silicious sponge. In his Monograph of the British Spongiada, Dr. Bowerbank has bestowed upon it the name above given; and has since, in the Proceedings of the Zoological Society' for 1869, figured the numerous minute sarcode spicula belonging to it. At the same time the essential basal skeleton of this sponge has hitherto only been obtained in a fragmentary condition, and it affords me much pleasure to give here a representation of its external form in its perfect state. The specimen figured was completely immersed in the hardened mud filling up the interstices of a dead mass of Lophohelia prolifera var. anthophyllites, and necessarily required some careful manipulation in its extrication. As will be observed, the skeleton of this sponge is composed of a series of infundibular netted tubuli branching out from one another and occasionally coalescing. In the condition in which it was taken, it was almost too much to expect to find the spicula of the sarcode also upon it, and such proved to be the case; but as that portion of its history has already been made known to us by Dr. Bowerbank, this circumstance was of minor importance; and we deemed ourselves only too fortunate to obtain the basal scaffolding intact. The figures of the sarcode spicula accompanying the illustration of this specimen, are copied from those by Dr. Bowerbank, given in his Monograph of the Siliceo-fibrous sponges in the 'Proceedings of the Zoological Society' for 1869.

Aulodictyon Woodwardi, W. S. Kent, nov. gen.* et sp.

From among the branches of the same mass of Lophohelia prolifera, which has already been referred to as yielding me so many new forms, I have yet to record another one, which in addition to being a new species must constitute the type of a new genus.

This sponge occurs in small fistulose ramifications, bridging over the minor interspaces between the branches of the coral to which it is attached. It possesses a certain exterior resemblance to Farrea, but differs from it in the following particulars :-In Farrea the basal skeleton is composed of a single reticulated lamina, in the sarcode investing which, according to Dr. Bowerbank, verticillato-stellate spicula and other minute forms are found. In Aulodictyon, on the contrary, the basal skeleton consists of a complex reticulated tube, between and continuous with the primary meshes of which, an abundant network of coalescing simple hexradiate stellate spicula occurs (see Plate LXIV., Fig. 20): the minuter spicula of the sarcode are again of an entirely different type. These are also represented in the Plate. Most remarkable among them are the long attenuate forms, l.c. Fig. 21, having one extremity inflated and reflecto-peltate with a dentate margin, and the other attenuately and finely acuminate; these seem to fulfil the part of * αύλος, a tube ; δίκτυον, a net.

tension spicula, and are met with singly or in bundles of two or three together in the substance of the sarcode; occasionally, the dentato-peltate structure is replaced by a simple series of recurved hooks (see Fig. 22), and every gradation between the two varieties may be detected. Another minute and beautiful form of frequent occurrence must be referred to the "spinulo-quadrifurcate hexradiate stellate" type of Dr. Bowerbank: an illustration of this form is given at Fig. 24. Simple attenuate, free, hexradiate stellate spicula are also abundant, these often having the basal extremity of the perpendicular shaft slightly inflated as at Fig. 23. I devote this species to my esteemed friend and colleague, Mr. Henry Woodward.

To this new genus, Aulodictyon, must be referred the species figured and described by Dr. Oscar Schmidt as Farrea fecunda, the primary characters being essentially in harmony with those applied to the species just described, and only differing in detail. In Aulodictyon fecunda (Farrea, ditto, O. Sch.) the interspaces formed by the reticulations of the basal skeleton are more regularly quadrate, and of much larger size than in my species; the reticulations are also more distinctly canaliculated, and their "bosses" present the same imbricated or fir-cone like appearance characteristic of Farrea occa, while in A. Woodwardi the canaliculi are very obscure, and the "bosses" of the reticulations are perfectly smooth. The spicula of the sarcode also differ specifically. I have not succeeded in detecting in my last-named species the attenuate forms with one extremity acutely digitate figured by Dr. Schmidt as characteristic of Aulodictyon fecunda, and the minute spinulo hexradiate spicula of his appear to have their terminations trifurcate instead of quadrifurcate as in mine.

Dactylocalyx, Stutchbury.

A representative of this genus has been likewise taken, but I have not yet had leisure to determine its specific identity.

Fieldingia lagettoides, W. S. Kent, nov. gen. et sp.

This form is figured and described in the 'Annals and Magazine of Natural History' for September last.

In conclusion, I consider it requisite, in the face of the large series of this interesting group of sponges I have lately been afforded the opportunity of studying, to propose a slight modification of the system of classification which has up to the present time been accepted, and which, in consideration of the limited number of forms known until within a very recent period, was perhaps almost sufficiently significant.

Dr. Gray has proposed to distinguish this group by the name of the CORALLIOSPONGIÆ, its essential character being that the

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sponges belonging to it are structurally composed of anastomosing silicious fibres. This feature is evident in Euplectella, Aphrocallistes, Dactylocalyx, &c., but is not applicable to such species as Hyalonema and Pheronema, or the recently described Askonema, Sympagella, and Lanuginella.

Dr. Wyville Thomson has proposed to distinguish all these forms, taken together, by the name of the VITREA; but the diagnosis he gives is wanting in correctness, and his order must necessarily make room for a more carefully drawn up and more trustworthy one. One of the primary distinctions of his VITREA is,*" that all the spicules of these sponges, without exception, whether of the skeleton or of the sarcode, are referable to the hexradiate type." Such is by no means the case, and is, in short, entirely out of harmony with existing facts. This is fully shown in the simple hair-like spicula forming the greater portion of the skeleton of Åskonema, in the long anchoring forms and the short fusiform ones of Pheronema, and in the various attenuate varieties peculiar to Aulodictyon Woodwardi and fecunda. Indeed, it is difficult to select any species in which the diagnosis laid down by Dr. Thomson holds good. If the forms just summarized are referable to the hexradiate type, so are the simple acerate ones of Spongilla, and the term VITREA may be applied with an equal amount of justice to every other group of the silicious sponges; but it being clearly evident that no such division as the one proposed by Dr. Thomson really exists, we are necessarily driven to seek further for a more carefully and correctly characterized diagnosis.

Dr. Oscar Schmidt, in his fine memoir already quoted, proposes to distinguish the whole series under the title of the HEXACTINELLIDE, from the fact of all the species sharing in common the possession of hexradiate spicula; though, at the same time, he does not commit himself, like Dr. Thomson, to the assertion that every spiculum is referable to that hexradiate type. This as a primary order or division is so natural, and the name is so fully suggestive of the common character by which Dr. Oscar Schmidt proposes to distinguish the group, that I shall not hesitate henceforth to adopt it, and most naturalists will, I think, recognize its importance and appropriateness.

Subordinate to this primary order, Dr. J. E. Gray's division of the CORALLIOSPONGIE, including all those sponge forms with a coalescing or reticulate silicious skeleton, remains intact; while of equal value to this I propose to form a new sub-order, which I distinguish as the CALLICISPONGIÆ, to include all such cup- or sacshaped forms as Hyalonema, Pheronema, and Askonema, and which, while possessing the hexradiate silicious spicula characteristic of the

* See Philosophical Transactions' for 1869, and 'Annals and Mag. Nat. Hist.'

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