LAMELLIBRANCHIATA. 5 



bristle-bearing, radiating lines. Only the slightest chink exists in front of the 

 umbones for the passage of the byssus. In form somewhat resembling, in miniature, 

 that of the large northern Lima excavata. Differing from P. sublaevis, Pelseneer, in 

 the position of the ligament and the absence of crenulation on the hinge-plate, and 

 in the character of the prodissoconch, as well as the position of the adductor scar. 



ADACNARCA NITENS. 



(PL III., figs. 6-6c.) 

 Adocnarca nitens, Pelseneer, Voy. Belgica, Mollusca (1903), pp. 24, 41, pi. vii., figs. 83-88. 



Beyond a slight difference in form, which seems to be a variable feature, 

 judging from the few specimens obtained, there does not appear to be anything 

 to distinguish these examples from that figured by Prof. Pelseneer. This genus, 

 consisting at present of a single species, has a small, obliquely-rounded shell, of 

 thin texture, glossy, minutely radiately striated, of a dirty whitish colour, covered 

 with a thin periostracum. The edge of the valves within is minutely crenulated, the 

 crenulation at the sides being rather stronger than upon the ventral margin. The 

 hinge consists of a minute central resilium, beneath the beaks (figs. 6c, l), a slight 

 marginal ligament (figs. 6c, 2), and a minutely, transversely striated hinge-plate 

 (figs. 6c, 3). The largest specimen is 7 millim. in length, 6'5 high, and 4*5 in 

 diameter. 



Hut Point, Oct. 18 and 25, 1902. 



The position of the ligament is somewhat different to that of Crenella decussata, 

 Montagu, which is elongate and obliquely internal within the hinder dorsal margin, 

 under the striated hinge-plate. Otherwise the species appear to be conchologically 

 congeneric. 



LlMOPSIS GRANDIS. 



(PL III., figs. 7-7b.) 



Shell large, obliquely ovate, very flat, concentrically striate and very finely 

 radiately striated, white, clothed with a coarse yellowish, hairy periostracum ; umbones 

 small, acute, separated by a narrow ligamental area ; hinge-plate narrow, slightly 

 sinuate in the middle, with thirteen teeth in a small specimen, and probably about 

 twenty in the adult form ; interior of the valves very finely radiately striated, 

 excepting the outer margin, which is smooth and shining ; anterior adductor scar 

 small ; posterior much larger, elongate pyriform, bounded on the inner side by a 

 thickening of the shell which forms a ridge extending from beneath the umbones 

 beyond the scar almost to the margin of the valve. 



Length, 33 millim. ; diam., 12. 



March 4, 1904, near Antarctic Circle, 254 fathoms. 



Closely allied to L. marionensis, Smith, but larger and flatter, and also distinguished 

 by the peculiar thickened ridge down the posterior side of the interior of the valves. 



