312 



Perna nana. T. parva, crassa, subquadrata, adunca, lamel- 

 losa, extus nigra ; margine ventrali sinuato ; angulo infero-posteri- 

 ori rotundato ; latere postico sinuato : area cardinali lata, 6-suI- 

 cata ; fissura byssali ampla, trigonalis : rr.argarita plumbaginea ; 

 limbo corticali angusto, pallido. Long, f ; alt. | ; lat. ^ poll. 

 Hob. Feejee Islands ; under stones. Drayton. 



The solidity and color of this little species will not admit of its 

 being confounded with any other species. It bears the marks of 

 mature age. 



Pinna senticosa. T. cuneata, sub-inflata, postice oblique 

 rotundata, purpureo-nigricans ; margine dorsali sub-ascendente ; 

 margine ventrali prope apicem pendulo : area triangularis superior 

 costulis ad 7 radiantibus squamigeris (squamis semi-tubulosis) 

 instructa ; area inferior striis incrementalibus solum notata. 

 Long. 4J- ; alt. 2^; lat. 1 poll. Hob. New Zealand. 



Its general appearance is that of P. seminuda ; but it is 

 smaller, much darker, the ventral margin is less arcuated, and 

 the scales much less numerous and regular. 



Mr. Ayres made some statements tending to show that 

 his species Cottus variabilis is distinct from C. Grcenlandicusy 

 of which Mr. Girard has regarded it as the young. 



C. Grcziilandicus^ he said, is a northern species ; south of 

 Cape Cod it is very rare, and had never been seen in Long 

 Island Sound, whereas C. variabilis is the only species of Cottus 

 found in Long Island Sound. It is seldom more than six inches 

 long, whereas C. Grxnhmdicus is much larger. The under 

 surface of C. GrcBulandicus has a number of circular, white 

 spots, which Mr. Ayres had never seen in variabilis. In Grmn- 

 landicuSy the head is one third larger in proportion to the body, 

 whereas, if variabilis were the young of this species the head 

 should be proportionally larger than in the adult. In variabilis 

 also the pyloric cssca are much shorter than in Grccnlandicus. 



Mr. Girard replied, that he had remarked that he thought two 

 species had been confounded under C. Grcenlandicus, and he 

 should be pleased to find one of them to be that described by 

 Mr. Ayres as C. variabilis. 



Dr. Burnett announced that he had recently discovered in a 



