REPORT ON THE LAMELLIBRANCHIATA. 93 



wliicli arc faintly rayed. The valves are comj^ressed, especially in young shells, and 

 gape at both cuds. The anterior dorsal margin is moderately oblique, very slightly 

 convex, the posterior being rather more horizontal and generally a little concave. The 

 anterior side, which is a trifle shorter than the posterior, is rounded at the extremity, tin- 

 hinder side terminating more sharply at a point rather low down, where a feeble ridge 

 radiating from the umboncs terminates. The ventral outline is widely arcuate, and 

 ascends a little hioher in front than behiiid. The two teeth of the right valve are both 

 bifid, erect, and divergent from one another. The left valve also has two teeth, one 

 erect, cleft at the top, similar to those in the right valve, the other being less conspicuous, 

 oblique, thin, lamellar, almost obsolete in some specimens, and situated l)eliind the mort- 

 prominent tooth which fiills just lieneath the uml)o. The muscular scars are large, about 

 equal in size, the anterior being usually of a more elongate form. A third smaller deepish 

 scar is situated beneath the hinge-line, a little in advance of the teeth. The 25allial sinus 

 is in every case deep, although not always equally so, and is irregular at times in form. 



Psammohia convexa, Eeeve, is undoubtedly the same species as the present. The 

 two specimens figured in the Conchologia Iconica are rather thick old shells, and a trifle 

 more convex than usual, Init answer the above description in every other detail. 



Tlie Tasmanian Psammohia zonalis, Lamarck, is very closely allied, and perhaps 

 scarcely w^orthy specific separation, but may be distinguished thus. It is somewhat 

 smaller, not usually quite so glossy, more strongly striate, especially at the posterior end 

 and near the ventral edges, and generally of a less pinkish tinge. With Psammohia 

 zonalis I have no hesitation in uniting Psammohia tellinceformis, Deshayes, Psammohia 

 puella, Deshayes, and Psammohia striata, Deshayes, the last being, I believe, a manuscript 

 name attached to specimens in the British Museum, from between West Hill and Cape 

 Upstart, Australia, collected by J. B. Jukes, Esq. 



Psammohia pallida, Deshayes. 



Psammohia 2'Mi<ln, Deshayes, Proc. Zool. Soc. Lond., 1854, p. 323. 

 Psammohia nialaccana. Reeve, Conch. Icon., vol. x. tig. 42. 

 Psammohia stiff u-sa, Reeve, loc. cif., fig. 54. 



Hahitat. — Station 188, west of Cape York, North Australia, in 28 fathoms; green 

 mud (Challenger) ; Red Sea (type in Brit. Mus.) ; Malacca (Reeve for Psammohia 

 malaccana and Psammohia siifusa) ; Lane Cove River, New South Wales (Brit. Mus.). 



There is no difference whatever excepting that of colour between Psammohia pallida 

 and Psammohia malaccana, the former being of a pale lilau tint, faintly rayed with a 

 darker hue, and the latter being purely white. Psammohia sujf'usa I regard merely as the 

 young state of a more highly coloured variety. The sculpture of all three is precisely 

 similar, the oblique striae terminating abruptly in an oblique line easily recognisable to 



