1870.] 



SENATE— No. 170. . 25 



if not to a total reversal, of many ideas hitherto considered 

 firmly settled in geology. 



From Mons. Cailliaud, Director of the Museum at Nantes, 

 we have received a fine collection, consisting principally of 

 boring shells in situ and of African fluviatile shells collected 

 by himself. 



The Smithsonian Institution has sent us, through Mr. P. P. 

 Carpenter, about three hundred and fifty species of shells, care- 

 fully named from type specimens in the Cumingian collection, 

 which will not only be of considerable value in themselves, but 

 enable us to identify and name correctly many species which we 

 have in quantities from former collections, made in the Society 

 and Sandwich Islands and elsewhere. 



We are also indebted to many other sources for valuable 

 additions, — to the Portland Society of Natural History for a 

 fine contribution of our coast shells, to Dr. Hensche for his 

 invoice of Prussian and other shells, and to Messrs. Mayo, 

 Layard, Bryan, Coronado, Bayley, Hubbard, Theobald and 

 Geale, for their several handsome and valuable contributions. 

 To all these contributors we desire to express our sincere thanks 

 for these and other kind favors received from them. 



The work of arranging and cataloguing the collection is still 

 going on, though this is necessarily a slow process, under the 

 rules we have adopted, by which we place no species on the list 

 which has not been mounted or about the name of which we 

 have any serious doubt. 



In terrestrial genera our most extensive genus is Helix, as 

 established by the older writers. Of this we have consid- 

 erably over thirteen hundred species, carefully named and 

 mounted, and these we are now engaged in endeavoring to 

 arrange and classify under new and better generic relations, 

 the many attempts by others to make a proper arrangement 

 having in most instances failed to commend themselves to our 

 judgment. We have as yet made but little progress in this 

 work, but propose during the coming year to make it the most 

 prominent object of our labors. We have also made consider- 

 able progress during this term, in arranging the Naiades under 

 several new genera, based mainly upon anatomical considera- 

 tions, our large collections of Unios, Anodons and Alasmodons, 

 in alcohol, affording us many facilities in this respect. We 

 4 



