144 ANATINID^. 



circular ossicle clasping vertically the two valves. This is 

 Hobson's choice ; for we presume that all malacologists are 

 aware that no other genus except Anatina is armed with this 

 singular distinction. There can be no mistake, as we have in 

 our cabinet the ossicles separately displayed, and they prove by 

 their identity that the " costellata" and " abbreviata" are the 

 scions of the type, the latter being the young, and the former 

 a variety. Many bivalves of the same species differ much more 

 in their varieties ; for example, the strongly punctured, and 

 the nearly smooth Lepton convexum. Brown in the first in- 

 stance placed this genus and species properly as the Anatina 

 brevirostris , but unfortunately, to truckle to the fashionable 

 nomenclature of the day, he changed it to Thracia brevirostra ; 

 but it is probable Olivias specific title has the priority. 



For what is known of the animal we refer to the ' British 

 Mollusca/ under the titles Necera cuspidata, N. costellata and 

 N. abbreviata. If the diligence of malacologists had been a 

 little more awakened to the observation of the conspicuous 

 ossicle, they might have spared themselves some trouble by 

 depositing their articles in genera already constituted, and 

 singularly appropriate. 



This species is taken sufficiently abundant on the Scotch 

 coasts. 



A. GRANULATA, nobis. 



Corbula ? granulata, Nyst and Westendorf. 



Poromya granulata, Brit. Moll. i. p. 204, pi. 9. f. 4, 5, 6. 



This is the Poromya of authors. To prevent repetition we 

 refer to our general remarks on the Anatina cuspidata. We 

 are almost afraid, that in admitting this species as distinct 

 from Anatina convesca, some error may be committed. We 

 have most carefully examined the hinge of the two, and find 

 it essentially the same ; both have the ossicle and their poste- 

 rior extremities bi-angulated ; they have the same shagreen- 

 like points or punctures in the test, increasing in intensity at 

 the margins; the siphons have the similar short character, 

 and are in like manner ornamented with cirrhi or filaments of 

 different lengths ; both present on each side the broad amal- 



