ft On the h s Applied to Pisidiwn, 



XVI. On tht Names Applied to Pisidium^a Genus of Corbicu- 



l'.v Tkmim.k PatKK 

 Load September 5l)i. 1369. 



The . Hum was characterized by CPfeiffer* in L821. 



1'iitil the year 1 V <»1 the species belonging to this genus were 

 iws: By Mullerf (1774) under Tellina, by Sco- 

 polij (1777) under Sphxrium, by Poli§ (1791) under Oardium, 

 and by Draparnaud| (1801) under Qyclaa {Sphcerium). 



1 Bhall now review what has been done since that time. 



Phygemoda. 



In 1820 Rafinesque^f divides the OorbiculodoB into four subge- 

 i. and places the Bpecies of Pisidium under the bead of the 

 Bubgenus Physemoda, which he characterizes thus: — 



"One intermediary tooth in one valve; shell somewhat trans- 

 jal." 



Etafinesque's arrangement has never been adopted; the charac- 



are insufficiently expressed, and are based solely upon the 



i parts of the animal. Moreover, he is unfortunate in the 



ii of one of the two Bpecies winch he as types of his 



Bubgenus, namely, I u lacu&tru, which is a Sphwrium. 



<»alih'ja. 



Thi ■ to bi' much uncertainty concerning this name. 



Dean -"-1 i places it under the synonomy of Pisum (Pis- 



.and n lit as having been described (1889) in the 



lenza Zoologica.ft He also quotes Philippi.ft Des« 



irth< r j inder the synonymy of Pisum I Pisidium) 



' '■■■ et Nat, t., 819. 



Bril Ifni Oat Oonohlf, ! 



' I Ironso Coita, 1889. 

 I alllppl, Boom. Y...II. sh-ii. II. 214, 1844 

 I '" ' ' "• . Brit Slus. (at. ConohiC, 2*79. 



