224 Transactions. — Zoology. 



boscis. No oral tentacles or veil, and no odontophore or buccal armature of 

 any description. 



This is the commonest Nudibranch in Auckland harbour, and is parti- 

 cularly abundant in the winter and spring months. It is usually found in 

 sheltered rocky places, in tide-pools, or under stones. The spawn is de- 

 posited in the form of a few-coiled spiral, and is generally seen in the 

 months of June, July, and August. 



Art. XXV. — On a neiv Genus of Opisthohranchiate MoUusca. 



By T. F. Cheeseman, F.L.S. 



[Read before the Auckland Institute, l&th August, 1880.] 



In some tide-pools near the Tamaki heads, in Auckland harbour, I have 

 repeatedly obtained specimens of a curious little Opisthobranch, that ap- 

 pears to me to be not only undescribed, but also to form the type of a new 

 genus. The following is a description. 



Melanochlamys cylindkica, nov. gen. 



Body elongated, almost cylindrical, 1-1^ in. long; colour a deep rich 

 velvetty black. Cephalic disc narrow oblong-quadrate, slightly expanded in 

 front, so as to project over the foot and mouth, truncate behind. Mantle 

 small, entirely concealing the shell, at its posterior end 2-lobed and with a 

 large gaping orifice. Foot large, with ample side-lobes, which are folded 

 up to the sides of the head-disc and mantle, leaving, however, the back ex- 

 posed. Shell quite internal, triangular, spire minute, inner lip with a 

 small spoon-shaped projection. Branchiae minute, situated far back on the 

 right side under the mantle. Gizzard very large and muscular, without 

 calcareous plates. Odontophore apparently wanting. 



I assume that the proper position of this animal is with the Philinidse, 

 with which it agrees in most of its characters. It differs, however, in 

 having no odontophore, and in the gizzard not being strengthened with cal- 

 careous plates. Aglaia (of Eenier), appears to be its nearest ally ; but lam 

 unable to place it in that genus, as it differs from the species figured in 

 Adams' " Genera " in being much more elongated, in the cephalic disc 

 being larger and projecting beyond the foot, in the branchije being smaller 

 and always concealed by the mantle, and in the side-lobes of the foot being 

 closely appressed to the sides of the animal, and not spreading. 



In addition to the specimens collected by myself I have examined some 

 obtained by Mr. G. M. Thomson near Dunedm, and kindly forwarded to 

 me by Prof. Hutton. Very probably it will be found to be common in suit- 

 able localities all round our shores. 



