REPORT ON THE LAMELLIBRANCHIATA. 283 



Linea cardiuLs mediocriter lata, iu medio sulco ligamenti clongato arata, utrinquo trans- 

 versim minute striata. Pagiua intci'iia uitida, microsco])ice subpunctata, marginc pcstico 

 cremiliitd. 



This species has the form of certain Modluhn, the anterior side being produced 

 upwards so that the beaks are not apical. It is thin, white, somewhat glossy, moderately 

 tumid, and irregularly pear-shaped. The anterior side is slightly incurved where the 

 byssus would pass between the valves. The hinder margin is broadly excurved and the 

 lower outline well rounded. The umbones are small, terminate in a remarkable, obtuse 

 shield defined by a raised edge or collar. They incline towards the front, and arc much 

 nearer that end of the hinge-plate than the posterior. This is rather broad, bears a con- 

 spicuous long ligamental groove commencing in front under the beak and extending 

 backwards in a slightly oblique direction, and both in advance of the furrow and behind 

 it is finely striated across. The interior of the valves is glossy, minutely subpunctate, 

 and has the posterior margin armed with a few denticles. The exterior sculpture consists 

 of fine lines of growth, coarser concentric lirse, and radiating ridges, which appear to vary 

 in number in difi"erent specimens. 



Length 4i mm., height 6, diameter 3. 



Habitat. — Prince Edward and Marion Islands, in 100 to 150 fathoms (about 1200 

 miles south-east of the Cape of Good Hope). 



This species probably attains larger dimensions than those given al)ove. It differs 

 from the typical species of the genus {Dacrydium vitreum) in having the hinge-plate 

 striated across in front of, as well as behind the beaks, in the character of the ligamental 

 furrow, and in the tips of tlie um1)ones. 



Family P i x N i D ^. 

 Pinna, Linne. 

 Pinna tasmamca, Tenisou- Woods (?). 



Pinna tasmamca, Tenison- Woods, Proc. Roy. Soc. Tasniau., l^'ri, p. 161. 

 Habitat.— Citation 1G2, off east Moncoeur Island, Bass Strait, in 38 fathoms; sand 

 and shells. 



The single specimen from this Station accords very faii-ly with Mr. Teuison-Woods 

 brief diagnosis ; but, where so much depends on form in the determination of species, it 

 is almost impossible to identify with certainty without a good illustration or reference to 

 the figure of a closely allied form. The specimen at hand is very like Eeeve's figure of 

 Pinna, carolinensis^ (^^ Pinna subviridis. Reeve), botli as regards outline and colour. 

 It differs, however, in having fewer ridges and much larger scales. There are five 



1 Conch. Icon., vol. xi. \A. \\\\v. fig. 66. 



