individuals. As regards the Australian species, this is increased by the fact that in the only two collections hitherto made, the Inocerami could not be compared, owing to Prof. M'Coy's abbreviated descriptions' being unaccompanied by figures. One of Prof. Liversidge's specimens is apparently I. Marathonensis, Etheridge, at least, my father believes it to be identical with the species so named by him in the Daintree Collection. It was obtained at "Landsborough Creek, a tributary of the Thomson River, and no great distance from the Flinders River waters." The second, Inoceramus, approaches the ordinary cretaceous species I. problematicus, d'Orbigny, or I. striatus, Mantell, but is more deltoid. From the same locality as the last.

In the same blocks with these Inocerami is a well-marked bivalve possessing the characters of Aucella, Keyserling, as laid down by the latter and the late Mr. Stoliczka,3 and of which a more detailed account is given below. The Monotis-like bivalve need not be referred to further than to say that, except the partial outline of the shells and the radiating fine ridges, no other characters are distinguishable.

Passing to the Cephalopoda, we have, first, the remains of a large shell, a portion of a whorl, on the reverse of which the Monotis-like ivalves are preserved. It is possible this may be a well-grown example of Moore's Crioceras Australe, with the ribs much more widely separated than in the figured example, but as the late Mr. Moore stated that they increase in the distance apart from one another, in the adult, this will not affect the question.

In the same blocks of stone with the Inocerami and the Aucella are two other well-marked Cephalopods. The first of these corresponds in every way with Prof. M'Coy's description of his Ancyloceras Flinders so far as the very terse remarks made by the former will enable one to judge. Here again we lack a figure, and the determination must remain in doubt. Although only a very small portion of the entire shell, it represents an individual of some size, in which the ribs fork on the sides, as described by M'Coy, and with a row of large, much compressed tubercles on the sides of the back. The section of our specimen is elliptical, but unfortunately that of A. Flindersi is not given by M'Coy. Loc.-Landesborough Creek.

The last specimen to be referred to is only a fragment. It may be only a small Ancyloceras, or a portion of a Hamites. The

1 Trans. R. Soc. Vict., 1866, vii, p. 50.

2 Quart. Jour. Geol. Soc., xxviii, p. 343, t. 22, f. 1.

3 Pal. Indica, iii, p. 390.

Quart. Jour. Geol. Soc., xxvi, 1870, p. 257, t. 15. f. 3. 5 Annals Nat Hist. 1867, xix, p. 356.

ribs on the back are in bundles of three, proceeding from a series of single nodes or tubercles at the sides; here and there a rib will be much stronger than the others.

The following is the detailed description of the Aucella.
Genus AUCELLA. Keyserling, 1846.

(Reise in das Petschora-Land, p. 297.)

Gen. char. "Obliquely elongated, inequivalve, of thin structure, pearly within, and with concentric sulcations externally; left valve strongly convex, with incurved beaks, a short posterior and an almost obsolete anterior ear, represented by a slight internal thickening; margin of shell in front below the beak insinuated; right valve flat or slightly convex near the umbo, with a small indistinct posterior and a still shorter anterior ear, generally a little twisted, and separated from the margin below by a deep byssal sinus; hinge line in both valves straight, short, and in the right valve usually with a small blunt tooth; ligament external, linear; muscular scars small, posterior submarginal, anterior placed near the ear, and often almost obsolete." (Stoliczka).1

Obs. I have quoted Dr. Stoliczka's description of this interesting genus, as being the best and most comprehensive with which I am acquainted; it is to all intents and purposes the same as the original by von Keyserling.

By most authors Aucella is said to be a Jurassic genus, but Eichwald believes the rocks from which the original examples were procured by Keyserling to be of Cretaceous age. Species definitely known to be of this period have been described by Stoliczka, Gabb, Conrad, and others, and there now appears to be no doubt of its existence during the epoch in question.

The late Mr. F. B. Meek has very justly said that Keyserling's genus has not been so generally adopted as it should have been.

convex.

AUCELLA LIVERSIDGEI. SP. NOV.

Sp. char.-Obliquely sub-deltoid, very inequivalve, planoLeft valve convex, inoceramiform, gibbous, and narrowed about the umbo, expanding ventrally; beak or umbo prominent and much incurved anteriorly, greatly overhanging the hinge line; anterior side vertical, the margin almost straight, and when seen from the inside deeply insinuated under the beak; posterior side steep, obliquely expanding; posterior ear and hinge margin very short; ventral margin obliquely rounded; surface with faint concentric undulations, which become more apparent and laminar towards the ventral margin. Right valve gently convex or

1 Pal. Indica, iii. p. 390.

2 Pal. Up. Missouri (Smithsonian Contributions), by Meek and Hayden, 864, p. 53.

prominent about the umbonal region, flattened towards the ventral portion, obliquely rounded, with a larger and better developed posterior ear than in the left valve; anterior margin rounded; anterior ear more or less triangular, reposing completely in the insinuation of the anterior margin of the left valve, separated from the body of its own valve by a deep byssal sinus; beak small, but sharp and prominent; surface ornamented with concentric lamina of growth. Hinge line of both valves short, but longest in the right; no tooth visible in the interior of the right valve.

Obs. A very interesting and unlooked for shell, presenting all the characteristic features of Aucella. It will form a very important addition to the Cretaceous Fauna of Australia. No mention of the genus is made as occurring in any of the collections examined from time to time by Professor McCoy, nor did the late Mr. Charles Moore enumerate it amongst the secondary fossils described by him from North Australia.1

Aucella Liversidgei is undoubtedly allied to two of the types of the genus, A. Pallasii, Keyserling, and A. crassicollis, Keys. In possessing the obliquity and short hinge line, it resembles the former; the left valve has the general form of the latter species, and a similar much incurved beak, whilst the right valve in all its peculiarities is almost identical with that of A. Pallasii. The resemblance of our shell to and its intermediate position between the two species in question is very remarkable. A. Liversidgei is also allied to the Indian Cretaceous species A. parva, Stoliczka,* but the left valve in the former is more inoceramiform than in the latter, and more oblique.

In A. speluncaria, Schlotheim," there are radiating striæ, and our species is less deltoid and more regular, and there is no inflection of the ventral margin.

6

A. Hausmanni, Goldfuss, from the Zechstein of Scharzfeld, is a much more slender shell than the Australian species, less convex, and more elongate from the beaks to the ventral margin. Another species, A. Caucasica, Abich,' possesses fine radiating striæ, to say nothing of a larger ear in the right valve, a more pointed and prominent umbo in the left, and a generally different outline to the valves. There appears to be at least one very interesting

1 Australian Mesozoic Geology and Palæontology. Quart. Jour. Geol. Soc., 1870, xxvi, p.p. 226, 261.

2 Petschora Land, p. 299, f. 16, f. 1-7.

3 Ibid, p. 300. t. 16. f. 9, 12.

Pal. Indica, iii, p. 404, t. 33, f. 2-3.

5 See Geinitz, Dyas. t. 14, f. 5-6.

6 Mytilus, Petref. Germaniæ, ii, p. 168, t. 138, f. 4. Aucella, Geinitz,

Dyas. p. 72, t. 14, f. 8 5.

7 Zeit. d. Deutschen Geol. Gesellschaft, 1851, iii, p, 31, t. 2, f. 1.

British example of Aucella, the A. gryphæoides. J. de C. Sowerby, sp.,1 but it has a much larger umbo in the left valve, and the general characters of the right are quite different.

The last species with which I am able to compare A. Liversidgei is the American Cretaceous form A. Piochii Gobb,2 a very gibbous and thick shell through the valves, quite distinct from the Australian.

POSTCRIPT, Jan. 19th, 1884.

Since the above description was written, I have received for examination from Mr. R. L. Jack, Government Geologist for Northern Queensland, a very interesting collection of Cretaceous fossils, from Rockwood Station, Landsborough River, and other localities in Northern Queensland. They clearly belong to the horizon of the Queensland Cretaceous series denominated by Messrs. Daintree and Etheridge (Quart. Jour. Geo. Soc., 1872, xxviii, p. 325), the Hughenden Beds. Prominent amongst them was the shell I have above called Aucella Liversidgei, in all stages of growth and preservation, and also that referred to under the name of Monotis simply. I now find these shells to be only the opposite valves of the same species, and, in well preserved examples, both valves to be radiately as well as concentrically striate. More than this: these additional specimens have convinced me that the form, although a genuine Aucella, and therefore still of great interest, is not, as I had previously conceived, undescribed. It is none other than the Avicula Hughendenensis Etheridge (loc. cit., pl. 25, f. 3.), but the figure given in my father's paper does not convey a correct idea of the outline. Under these circumstances, therefore, the specific name will be Aucella Hughendenensis, Etheridge, sp. To the description given above, the following additions and corrections must be made. Both valves are crossed by fine radiating striæ, which give rise to a minute cancellation. In the left valve the striæ are more apparent below the beak, and die out on the body of the shell. In the right valve they are of a fluctuating or wavy character, and the concentric laminæ become frill-like.

1 Trans. Geol. Soc. P. ter. iv, t. 11, f. 3.

2 Pal. California ii, t. 32, f. 92.

[Two plates.]