86 AMERICAN JOURNAL 



Monograph of American Corblculadae, (Recent and Fossil.) By 



Temple Prijie. 8vo. &Opp. Smithsonian Institution, Washington. De- 

 cember, 1865. 



We have more than once acknowlerlged with gratitude, in these 

 pages, the prominent share wliich the Smithsonian Institution is 

 taking in rendering the study of American Conchology accessible 

 to all ■who take an interest in its pursuit. The present issue, 

 which is the first of a series which will include, when completed, 

 the entire Molluscous fauna of the United States, contains the 

 history of all the small fluviatile bivalves which, under the gen- 

 eric names of iSpha'rium {Cyclas) and Pisidium, are found in all 

 the temperate regions of the continent, as well as of their larger 

 prototypes the species of Corhicula and Oyrena inhabiting its 

 tropical portions. It may be truly said that this family has 

 never been studied in America, save by the author of the above 

 work, and that the characters of the species are almost utterly 

 unknown to us. These shells are so minute, and their study, 

 without the advantage of good figures in identifying them, so 

 unsatisfactory, that conchologists have been tempted to neglect 

 them for fields yielding a richer harvest. As this monograph is 

 the product of the ripe judgment and experience of a gentleman 

 who has spent his entire leisure for years in becoming thoroughly 

 acquainted Avith his subject, it may fairly be presumed that his 

 views of the synonymy of the species, etc., are correct — and, at 

 any rate, no one is competent to call them in question. We will 

 therefore content ourselves with a rapid summary of the work, 

 in order that our readers may estimate its importance to those 

 who will doubtless hereafter give more particular attention to the 

 subject of which it treats. In the preface, Mr. Prime states 

 that the American species of Corhi<nda differ from the foreign 

 ones in the palleal impression being terminated in a sinus, whereas 

 in the latter it is simple, and that the same distinction holds good 

 between the American and the foreign species of t'yrena ; yet 

 three fossil species of Corhicula from the Paris basin exhibit the 

 sinus the same as in our recent species. As these differences 

 indicate structural differences in the animals, Mr. Prime proposes 

 at a future time to characterize as new genera the American 

 Corbiculse and Cyreuie. 



The genus Sphaerium, Mr. Prime thinks, might be advantage- 

 ously divided into four genera, to include those with 



" 1. Shell solid, striae deep, beaks rounded ; example Sj^h. 

 sulcatum : Sph. solidum of Europe. 



2. Shell somewhat solid, striae light, beaks rounded ; example 

 tSph. rliomhoideum ; Sph. coriicuni of Europe. 



