397 Bulletin 5 27 



AT AN ASTASIA ISLAND. 79 



the hinge margin of a species, which I believe to be the 

 canaliculata . The greatest part of this shell is so thin, that 

 we are not surprised that it should have been comminuted ; 

 we should, however, expect to find part of the umbo and 

 the entire hinge fosset, but no trace of either has as yet 

 been discovered. 



6. Mactra. Numerous fragments of a small species which 

 is probably M. lateralis, nobis. All the specimens, however, 

 when perfect, must have been smaller than the average size 

 of those now existing on our shores. 



7. DoNAX. Fragments of a species of this genus seem to 

 be next, in point of frequency, to those of the Arc^, and 

 few were obtained nearly entire ; as far as I could 

 judge, by comparison, the species is the same with the D. 

 variabilis, nobis. Some of the fragments have not yet alto- 

 gether lost the fine purplish colour of the inner side of the 

 shell. 



8. Crepidula. a single specimen, too imperfect to ad- 

 mit of a specific decision. 



9. LuciNA. A single, young, and imperfect specimen. 



10. Arc.\. Bcvsides the species of Area above enume- 

 rated, there are some fragments of another species, proba- 

 bly now extinct upon our coast, or, if still existing, extremely 

 rare. It is possible this may prove to be the A. Candida, 

 Gmel. as it has intermediate smaller striae towards the an- 

 terior end. 



Fragments of several other shells were obtained from 

 the mass, but they were too imperfect to justify even the 

 hazard of a conjecture respecting their affinity. It will be 

 observed that all the species here mentioned are bivalves, 

 not the smallest determinable portion of a univalve was 

 observed : from which circumstance we may conclude that 

 the island is almost exclusivel)^ formed of bivalve shells, 

 and chiefly of the genus Arca. 



[J. A. N. S., Phila., ist Sen, Vol. IV, 1824.] 



