132 THE VOYAGE OF H.M.S. CHALLENGER. 



Venus (Gomphina) nndulosa, Lamarck. 



VcnHn undidom, Lamarck, Anim. sans vert., vol. v. p. G06, ej. 2, vol. vi. p. 370. 



Venu>s uudnhjxa, Plulippi, Abbild., vol. i. js. 39, pi. i. tig. 1. 



Ventts undnlosa, Sowerby, Thes. Concb., vol. ii. p. 738, pi. 158, fi,L;s. 142-146. 



Venus undidosa, Eeeve, Conch. Icon., fig. 126, a, h. 



Venus uvdidosa, Pfeiffer, Conch. -Cab., ed. 2, p. 186, pi. xxiii. fig. 3. 



Gumyhinu undulosa, Morcb, YolJi Cat., p. 19. 



Cliione undulosa, Deshaj'es, Cat. Conchif. Brit. Mus., p. 152. 



Chione (Marcia) undulosa, H. and A. Adams, Genera Moll., vol. ii. p. 423. 



Venus {Gomphina) undidosa, Eonier, Mai. P.liitt., 1865, vol. xii. p. 143. 



Tivula ujididosa, Angas, Proc. Zool. Soc. Lond., 1867, p. 922. 



w&x.l^ Cijtherea{Gonvp}iinu) moercld, Angas, Proc. Zool. Soc. Lond., 1872, p. 611, pi. Ixii. fig. 7. 



Habitat. — Station 187, near Cape York, North Australia, in 6 fathoms; coral mud. 



In the British Museum there are sj^ecimens of this variable yet easily recognisable 

 species from Swan River collected by Captain Mangles, R.N., and Mr Jukes, and a totally 

 white variety from Sydney. 



The shell described by Angas under the name Cytlierea [Gomphina) moerchi, from an 

 unknown locality, I believe to be an extreme variation of the present species. The type, 

 presented to the British Museum by the author, appears to me somewhat distorted at 

 the posterior end of the ventral margin, which gives rise to the slight sinuation at that 

 part. The composition of the hinge, the muscular scars, pallial sinus, lunule, and 

 external sculpture are absolutely identical as in Venus undulosa. The main distinction 

 is that of form. In typical specimens the umbones are situated somewhat in advance 

 of the centre, the anterior slope being in consequence shorter than the posterior. In 

 the example described by Angas they are as nearly as possible central, and the dorsal 

 margins about equal. The colour of this shell is also rather peculiar, the undulating 

 zigzag painting being pinkish instead of brown, which is the usual tint when present. 

 The wavy lines across the lunule and area are precisely similar as in certain undoubted 

 forms of this species before me. Another indication of its specific identity is the 

 presence of two somewhat interrupted rays which fall exactly in the positions as in 

 many normal examples, namely in a divergent manner from the umbones to the ventral 

 margin. The single Challenger s^secimen has a peculiar coating or pseudo-epidermis of 

 carbonate of lime of a fibrous nature, the fibres being at right angles to the surface of 

 the shell. 



Cijtherea, Lamarck. 



Cytherea [Callista) chione, Linne. 



Habitat. — Tenerife, Canary Islands, at a depth of 70 fathoms. 



This species is so well known that I refrain from giving any references or synonymy. 



