SHELLS. 259 



*201. Mytilus polyodontes. Quoy et Gaim. Voy. As- 



trol. iii. 462, t. 78, f. 15, 16. 

 Inhabits New Zealand. 



202. Modiola albicosta. Lam. ? 



Inhab. New Zealand, Cook's Straits. Dr. Dieffenbach ; 

 and Van Diemen's Land. R. Gunn, Esq. 



203. Modiola securis. Lam. ? 



Inhab. New Zealand. Dr. Dieffenbach. 

 Only a single small valve has yet been sent. 



204. Lithodomus truncatus. 



Inhab. New Zealand, in stones. Dr. Stanger. 



Shell oblong, subcylindrical, thin, short, and roundly truncated 

 in front, contracted in the middle, and rather produced and taper- 

 ing behind, covered with a dark brown periostraca ; umbones 

 rather prominent, inflexed ; inner side purplish, rather pearly. 



Easily known by the truncated appearance of the front end and 

 the prominence of the umbo. The hinder half of the shell is 

 covered with a coat formed of green regular laminae, perhaps alga. 

 Common in the Greywakke rocks on the East Coast. Dieffenbach. 



205. Modiolarca impacta. Mytilus cor. Martyn, U. C. 

 t. 77. Myt. impactus. Hermann, Naturf. xviii. 147, 

 t. 3, f. 5-8, xix. 183. Wood, Cat. 59, f. 40. M. 

 discors. Australis. Chemn. viii. f. 768. Modiola dis- 

 cor, Lam.vi.-p. 16. Myt. lanatus. Calonne. Cat. 43. 



Inhab. New Zealand. Dr. Solander. Bay of Islands. 

 Dr. Sinclair. East Cape. Dr. Dieffenbach. 



Fam. PINNID.E. 



206. Pinna Zelandica. Gray. Yale's New Zealand, 

 App. Gmel. 3166. Wood, Cat. 60, f. 10. P. 

 adusta. Gmel. ? 



Inhab. East Coast. Yate. Bay of Islands. Dr. Dief- 

 fenbach. 



Shell triangular, elongate, blackish; inside purplish pearly; 

 valves convex, with rather close longitudinal ribs, armed with 

 close, short, semi-cylindrical, hollow spines. Differs from P. squa- 

 mosa, in being smaller, black, and in the end being more truncate. 

 It may be Pinna adusta, Chemn. viii. 237, t. 91, f. 782. P. ex- 

 usta, Gmelin, said to come from New Zealand, by Humphreys, 

 and Manilla, by Chemnitz. 



s 2 



