REPORT ON THE LAMELLIBRANCHIATA. 83 



Length G^ mm., height nearly 5, diameter 3|, 



Habitat. — Off Royal Sound, Kerguelen Island, depth 25 fatlioms; also Prince 

 Edward Island, 150 fathoms, and j\Iarion Island, 100 fathoms. 



Variety. — This form is more compressed than the type, thinner, higher in proportion 

 to the length, with smaller, less inflated, non-eroded beaks, and the line cu'cumscribing 

 the lunule is less distinct. 



Length 7 mm., height 5f, diameter 3. 



Habitat. — Balfour Bay, Royal Sound, Kerguelen, in 20 to 60 fathoms. 



The specimens from Prince Edward and Marion Islands, which, I believe, belong to 

 this species, ax-e all young, and in this state do not exhibit any trace of a lunule. 



This species does not quite correspond in the hinge with the t}ijical form of Davila, 

 Davila 2^lci>ia of Hauley having in the left valve a small, anterior, lateral tooth, which 

 is absent in Davila iimbonata. The very insignificant emargination of tlie pallial line i."^ 

 equally apparent in both. 



Family S c R B I G-u L A R 1 1 D ^. 



Subfamily Semelik.e. 



Semele, Schumacher. 

 Semele amabilis, A. Adams. 



Semele amahilis, A. AJams, Proc. Zool. Soc. Lond., 18.53, p. 97. 

 Amphidesma amabilis. Reeve, Conch. Icon., vol. viii. pi. v. fig. 32. 



Habitat. — Station 189, Arafura Sea, in 25 to 29 fathoms, green mud (Challenger); 

 Port Curtis (A. Adams). 



This is a very elegant shell, and remarkable on account of the thin elevated and uji- 

 turned concentric lamellae which adorn the surface. It is somewhat longer than high, 

 moderately compressed, almost equilateral, white and stained with brown down the 

 posterior side of the left valve. The front dorsal slope is somewhat concave near the 

 umbones, then oblique and straightish, the posterior being a little arched and scarcely so 

 sloping. The ventral margin is regularly curved, and forms in front, together with the 

 dorsal edge, a broadly rounded end. The hinder extremity is more irregular, termin- 

 ating in an obtuse angle, and exhibiting more or less of an oblique truncation below the 

 angle. The two valves are not similar at the posterior part. In the left there is a 

 single broadish depression radiating from the beak, subparallel with and only a short 

 distance from the hinder dorsal marijin, causing a flexure in the concentric lamellae. In 

 the right valve there are two such depressions and a corresponding double sinuosity of 

 the lamellae. The lunular depression is pretty deeply lanceolate, and the hinder dorsal area 

 is also narrow, sunken, and defined by carinate edges. The sculpture consi.sts of the remark- 



