138 



VENERID^. 



riorly, where it has the purple color of the outside ; muscular and 

 pallial im[)ressions distinctly marked, the latter with an 

 acute sinus ; teeth divergent, the middle one in each valve 

 stout and triangular, the anterior tooth of the right, and 

 the posterior one of the left valve thin, and not easily dis- 

 tinguished ; inner margin crenulated. Length, three twen- 

 tieths of an inch ; height, one eighth of an inch ; breadth, 

 one sixteenth of an inch. 



This beautiful little amethystine gem, as it has Ijecn appropriately 

 called, is found in great almndancc on all the sandy shores of Mas- 

 sachusetts Bay. Colonel Totten also found it in Newport Harbor. 

 Beyond this its range is not known. [Fishing Banks (TFiV/w); 

 Green Island (5^//).] It was noticed by some of the early visitors 

 to New England, and specimens of it were sent home to England 

 among other curiosities. It is, therefore, not a little remarkable, 

 that a shell so long ago observed should have remained, until very 

 lately, undescribed. But it is only recently that it has been recog- 

 nized as a distinct species and described by Colonel Totten. It is 

 commonly regarded as the fry of the qua/iog- (^ Venus mcrcenaria'), 

 on account of its purple tip. But on close examination it will be 

 found to be a fully developed, mature shell, different in every im- 

 portant jjarticular from that species. It is a very interesting shell, 

 as being by far the least of any species of the genus known. 



Gemma Manhattensis. 



Shell small, triangular, solid, shining, beaks nearly central, grooved with re- 

 mote, concentric furrows, inner margin crenulated. 



Venus (Gemma) Manhattensis, Prime, Ann. New York Lye. vii. 482 (■\voodcut) (1852). — 

 Jay, Catak 4th ed. Suppl. 466. 



Shell quite small, elevated, nearly triangular, 

 with the apex nearly central and the ventral mar- 

 gin rounded, the posterior end more rounded tlian 

 the anterior ; valves rather solid, compressed, of 

 a straw color, shining, and very regularly fur- 

 rowed wnth distinct concentric grooves. Interior 

 white, the siphonal sinus very small, and the 

 margin clearly crenulated ; muscular impressions 

 quite distinct. Length and height one eighth 

 of an inch ; breadth, one sixteenth of an inch. 

 Found in East River, New York, near Hell-Gate, by Mr. Prime, 

 and by Mr. Sanderson Smith at Greenport, Long Island. 



G. Manhattensis. 

 Enlarged. 



