12 THE NAUTILUS. 



dred si)ecie?. Four genera are represented in America, three in the 

 U. S., and two in New Enghxnd. 



Genus Sphcerium, Scopoli, 



The genus S])h?erium was characterized under its present name 

 by Scoi)oli in 1777. It has borne some fourteen different names, 

 but lias been better known to conchologists. especially in Europe, 

 by the name of ('yclas, given by Bruguiere in 1792. Gray revived 

 the name of Sph?erium in 1847, and Mr. Prime was the first in 

 America to recognize its claims. There are seventy-five species 

 distributed world-wide; they are found in rivers, ponds, lakes and 

 ditches, in f;act, in all bodies of fresh water, but are more abundant 

 in species and in individuals in the northern parts of our country 

 than in any other section of the world. Four species inhabit Rhode 

 Island, and possibly more. 



170. — Sphcerium partumeium Say. 



I shall not attempt to give the synonymy of this, or any of the 

 species of this genus, or of the next to follow; it would be a weari- 

 some and a thankless task ; these shells ai'e so little known, and the 

 animals inhabiting them have been so little studied that the synonymy 

 is but an entangled mass of errors. For the benefit of those wdio 

 might desire to study deeper into the subject, and to post themselves 

 in regard to the views of authors who have written upon it, I would 

 refer them to Prime's "Monograph of American Corbiculidie," 

 published by the Smithsonian Institution, at Washington, D. C, 

 1865. 



Sphifirium partumeium was first described by Sav in Journ. Acad. 

 Nat. Sci., Philadelphia, ii, 380, 1822, under" the name of Cyclas 

 partumeia. It is distributed all over the U. S., east of the Rocky 

 Mountains, and its habitat is in stagnant pools and muddy ponds. 

 The animal is of a delicate pink, and the syphonal tubes of the same 

 coh)r. The shell is rounded-oval, thin, fragile and pellucid ; nearly 

 equilateral ; beaks central, calyculate approximate at the apex ; 

 epidermis glossy, light greenish or bluish in color ; interior of valves 

 light blue ; hinge margin nearly straight, curving gradually into 

 the anterior margin, but curving behind, so as to form an obtuse 

 angle, causing the posterior side to ajipear broader ; cardinal teeth 

 strong; lateral teeth much elongated. The young shells are more 

 compressed than the adult, and are of a light yellow color. Length 

 of shell, 9-20, height, 2-5, breadth, 4-15 of an "inch. 



(To be continued.') 



Numerous publications received will be noticed in our next 

 number. 



