- 12 - 



American Tertiarj: faiinas. Another interestinp- le- tra*e is tlie 

 . ocG"arrense of a foim that ap-arently shoiiLd be pliiced in the 

 genus Oooperella, from the t^'pical form of vAiieh it is sepa- 

 rated "by differences that are of at least sectional value. 

 Only two s-ecies of the genus have heen hnown, a recent soecies 

 "rom the Vest Ooast and another from the I'iocene of the Atlaxitic 

 Ooast . 



The geniiB Tellina also must he placed among the import- 

 ant genera, for it includes 15 species, distributed among siz 

 sections, Angul-^;'*. I'n.s thft Ip.rp-est number of s-oecics to its 

 cre'^.it, but the most cbiuid aiit forms are foi" er l-erisca and 



Koerella. ?he other Tellinacea present no unusual featiires from 

 a biological -ooint of vie'-. 



The reniaining- ^'eleodesiriscea are scattered among sev- 

 eral groups, The suoerfamily Solenacea is represented by a 

 sriecies of the genus Psarimosolen . A sinp-le fr: -'nientejry valve 

 belonging to an indeterminable s oecies of the genus 3pisula is 

 the sole representative of the i'aotridae. The Gorbulas are the 



only non-boring Ilyacea presc-., . :., ."'thour-h ine"^ r'-'!1--r" inly 



three species, two of them are ericeedingl^j prolific. ...e un- 

 usually favorable conditions liave -lermitted the ^recerva-tion 

 of several b-^riii-' "droraacea that usually are not foiu.rl in Tert- 

 i ary f aunal 1 it t s . 



