Shell depressedly conical, suborbicular, imperforate, rugosoplicate, subplicate, or nearly smooth, pale yellow, whitish or brown, clouded, striped with pale green, sometimes mottled white, and livid on the upper whorls; very distinctly spirally grooved, and crossed with much inclined diagonal lines of growth; whorls 6-7 generally undulately plicate at the suture, which is either impressed or overlapping; base very flat, acutely angled at the periphery, which is undulating or round, according as the whorls are plicate or not, spirally lirate with 5-7 spirally raised lines which are diagonally crossed with strongly marked lines of growth and very finely, almost squamosely undulately striate; periphery margined at the base; that is to say, there is always a clear marginal space between the lire and the edge; aperture subquadrate, much produced above; throat conspicuously enamelled; outer lip thin, margined within with a yellow line, and then generally a rich deep brown; base of throat wholly white, or with a broad white band; columella conspicuously orange, and spirally grooved posteriorly (visible under the lens); the upper part of the throat sometimes brown, sometimes white, but always enamelled. Dimensions of the largest specimen diameter of base 17, alt. 14, of the smallest 11-7 millimetres.

It is worthy of remark that in this variety there is little or no thickening of the base, which is denticulate at the edge, but not lirate within; and finally, that the deep brown color is a thick vitreous translucent substance easily separated from the shelly outer covering, and when the basal part of the throat is broken away, it is seen to extend like a broad margin of brunswick black round the upper interior.

The operculum is a pale, translucent yellow, oblong, few whorled, and an almost marginal nucleus.

The odontophore (lingual ribbon) is a very fine, glassy, narrow, flattened tube, about 20 millimetres long, and lying in a coil just below the red fleshy buccal mass. Inside this tube the teeth are affixed to a somewhat thickened transparent membrane. The teeth are very numerous in sets or chevrons of seven; that is

to say, three in a diagonal line on each side from a central tooth. They are perfectly vitreous, colorless, and transparent. The central tooth is long-curved and sharp-pointed, with two very small lateral cusps. The first two laterals are also apparently provided with cusps. The outer teeth have a broad summit, which is tridentate. Thus it differs from the dental formula given after Wilton in Woodward's Mollusca (Tate's edit. 1871, p. 252), and from that of Gray (Guide to Mollusca in Brit. Mus., 1857, p. 90). The tube of the odontophore is so very thin that the upper membrane is easily destroyed in drying.

RISELLA NANA. R. t. arbiculari, subconica, ad periphariam, acute angulata, cinereo-virente; lineis longitudinalibus fuscis radiantibus; anfr. planiusculis; infima facie plana, concentrice sulcata, violarescente; umbilico nullo. Lamarck 1822, an m. s. verteb., gen. Trochus n. 67. Alt. 12, diam. max. 16 mil.

This species or variety, which, as I have said, takes the office of female to R. aurata, differs in being a larger and more solid shell with flattened smooth whorls which are seldom rugose, and seldom with the regular plaits of the male variety. It is sometimes much corroded and rough, and is either high and obtusely conical with an obtusely angled periphery, or depressed and very acutely angled. One constant feature it possesses, unless where much corroded, and that is the transverse sloping brown or black lines on a grey or brown ground. It has the same lirate flattened base, with the smooth margin, which is common to all the species known to me. The mouth has a highly polished enamel, variously striped or clouded, yellow and brown, but much paler generally, and with less brown than the preceding variety. It is a larger shell in every way, more solid, and with a thickened base. The odontophore is similar to the last described in the number and arrangement of the teeth, but they are less crowded and longer. It is longer and broader, and like the preceding, a tube.

Though the above differences are plainly marked in the extremes of both varieties, yet it must be admitted that gradations from one form to the other may be found. The spiral lire with plaits in

R. aurata, and the smooth whorls with diagonal lines of color in R. nana are the most constant distinction.

R. melanostoma is marked with R. aurata by Gray (loc. cit.) as variety of one species. This I believe. At any rate, the former is unknown to me. It is the oldest name, but from the imperfect diagnosis of Chemnitz it is impossible to identify the shell meant as a Risella.

R. plana, Quoy, is a very depressed solid angular lirate and plicate species with a yellowish white mouth. It is longer than the preceding, and its specific characters seem very constant. The animal I have not seen. The shell is found all round the Australian coast from Port Stephens to S. Vincent's Gulf.

R. lutea, Quoy, I believe to be only a corroded and brackish water or male variety of the preceding; but I know little of the living habits of the species. In Dr. Cox's extensive collection, I noticed the shells named R. lutea which appeared to me a common form of R. nana or aurata, but adult or perhaps more correctly in old age. It is corroded, and the marginal space on the base is not visible. It is common in Tasmania, and breeds readily with R. nana. Mr. Angas says (Zool. Proc. 1867, p. 209), this species, the most conical of the genus, is common on the rocks outside Port Jackson, and along the coast to Kiama and Jervis Bay. Mr. Crosse (loc. cit, p. 238) says, on the authority of MM. Q. and G., that it is found throughout King George's Sound, but principally in the little salt creeks. The only good figures, says M. Grosse, are those of Kiener, in his monograph of the genus Trochus-but there is no description as the work is not completed.

Thus we should have only two species of Risella, with male or female varieties of both.

It is possible that these two species may even yet be reduced to one; but I respectfully beg the attention of naturalists to the fact that the sexual differences are marked by differences in the shells. This may open up a most important fact for the whole of our conchological nomenclature. I also call attention to the remarkable

manner of breeding of hermaphrodite mollusca. As yet, we know little or nothing of the physiology of reproduction under these peculiar conditions, and I submit that most important physiological and zoological facts are contained therein, bearing on the whole question of evolution. The subject may be said to be at our doors, and may be studied with the greatest ease by anyone who gives it a careful attention. I have written this paper in the hope of drawing other observers into this most inviting and interesting

field.

Shells collected during the Chevert Expedition, with Descriptions of the New Species, by J. BRAZIER, C.M.Z.S.

FAMILY SCALARIDE.

1.-SCALARIA REPLICATA.

Scalaria replicata, Sow. Jun., Proc. Zool. Soc., London, 1844,

Sowerby, Thes. Conch., vol. 1, p. 84, pl. 32,

Hab. Darnley Island, Torres Straits, 10 fathoms, sandy mud.

2.-SCALARIA PHILLIPPINARUM.

Scalaria Phillippinarum, Sowerby, Jun. Proc. Zool. Soc., London,

1844,
P. 12.

Thes. Conch., vol. 1, p. 85, pl. 32,

Hab. Darnley Island, Torres Straits, 10 fathoms, sandy mud. This species is also found in Port Jackson.

3. SCALARIA IRREGULARIS.

Scalaria irregularis, Sowerby, Proc. Zool. Soc., London, 1844,

Hab. Bet Island, Torres Straits, 11 fathoms, coral and sand. Specimens also found on the beaches inside the reefs after gales.

4.-SCALARIA TENUI-COSTATA.

Scalaria tenui-costata, Sowb. Jun., in Sowerby Thes. Conch., vol. 1, p. 87, pl. 34, f. 76, not in Proc. Zool. Soc., London, 1844. Hab. Bet Island, Torres Straits, 11 fathoms, coral and sand.

5.-SCALARIA RUBRO-LINEATA.

Scalaria rubro-lineata, Sowerby, Thes. Conch., vol. 1, p. 91, pl. 34, f. 83.

Hab. Darnley Island, Torres Straits, 20 fathoms, sandy mud.

Scalaria delicatula, H. Adams, Proc. Zool. Soc., London, 1869, P. 274.

subnudata, Sowerby, Reeve, Conch. Icon., pl. 14, sp. 11. Hab. Darnley Island, Torres Straits, 20, 30 fathoms, sandy mud. Scalaria delicatula pre-occupied by Crosse, 1864.

7.-SCALARIA TURRICULA.

Scalaria turricula, Sowerby, Jun., Sowerby, Thes. Conch., vol. 1, p. 92, pl. 34, f. 88.

Hab. Princess Charlotte Bay, North-East Australia, 13 fathoms, sand; Bet Island, Torres Straits, 11 fathoms, coral and sand.

8.-SCALARIA CASTA.

Scalaria casta, A. Adams, Proc. Zool. Soc., London.

Sowerby, Reeve, Conch. Icon., pl. 11, sp. 86. Hab. Darnley Island, Torres Straits, 20 fathoms, sandy mud.

9. SCALARIA AURITA.

Scalaria aurita, Sowerby, Jun., Proc. Zool. Soc., London, 1844,

Hab. Darnley Island, Torres Straits, 20 fathoms, sandy mud. One specimen found.