REPOKT ON THE LAMELLIBRANCHIATA. 2U3 



the lateral outline in a rounded angle. The side itself is only slightly excurved, whilst the 

 opposite margin is semicircularly arched, as is also the basal edge. The umbones are 

 slightly elevated above the hinge-line, and terminate in obtuse circular glossy shield-like 

 bosses. The hinge is composed of two cardinal teeth in the left valve and a single one in 

 the right. They slope forwards and are strong for so fragile a shell. In the right valve 

 there is also an elongate slender lateral tooth, parallel with the hinder dorsal margin, 

 from which it is separated by a narrow furrow, into which fits a corresponding tooth in 

 the other valve. The internal ligament is small, situated immediately beneath the obtuse 

 apices and behind the cardinal teeth in both valves. The interior is rather glossy, and, 

 owing to the thinness of the shell, exhibits the radiate character of the external sculpture, 

 which produces a crenulate margin to the valves. 



Length 6 mm., height 6, diameter 4^^. 



Habitat. — Station 194d, Royal Sound, Kerguelen Island, in 28 fathoms ; volcanic mud. 



This curious little species externally is not unlike a delicately sculptured Cardium. 



Kellia adamsi, (Angas). 



Lepton adamsi, Angas, Proc. Zool. Soc. Lond., 18G7, j^p. 910, 911, and 928, pi. xliv. fig. 11. 



Habitat. — Port Jackson, in 2 to 10 fathoms. 



Only a single right valve in poor condition was obtained. This species is wrongly 

 placed in the genus Lepton, for the hinge-characters are (|uite different from those of that 

 genus, but agree perfectly with those of Kellia rotunda, Kellia suborbicularis, &c. No 

 doubt it was the punctate surface down each side of the valves which misled Mr. Angas 

 in the location of this interesting species. 



Montaciita, Turton. 

 Montacuta paula (A. Adams) (PI. XII. figs. l-\b). 



P(/thtna jjaula, A. Adams, Proc. Zool. Soc. Lond., 1856, p. 47. 

 Pijthina peculiar's, A. Adams, up. cit., p. 47. 



Habitat. — Station 188, south of New Guinea, in 28 fathoms (Challenger); Paine 

 Island, Torres Strait (Adams); Ceylon for Pythina pecidiaris (A. Adams). 



I have very carefully studied the two forms, which I here unite as one species, and 

 have come to the conclusion that the shell described as Pythina peculiaris is merely 

 unusually distorted. The " tout ensemble " of the specimen, with the exception of the 

 outline, is quite like that of Pythina paida, it is similarly sculptured, of the same texture, 

 and has precisely the same dentition. This consists, in one valve (which may be regarded 

 as the right), of two widely divergent cardinal teeth separated from the dorsal margins 



