12 THE NAUTILUS. 
dred species. Four genera are represented in America, three in the 
U.S., and two in New England. 
Genus Spherium, Scopoli. 
The genus Spheerium was characterized under its present name 
by Seopoli i in 1777. It has borne some fourteen different names, 
but has been better known to conchologists. especially in Europe, 
by the name of Cyclas, given by Brnguiére i in 1792. Gray revived 
the name of Spheerium. 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 fact, 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.—Spherium 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 are 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 who 
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 Corbiculidze,” 
published by the Smithsonian Institution, at Washington, D. oe 
1865. 
Spherium partumeium was first described by Say in Journ. Acad. 
Nat. Sci., Philadelphia, ii, 380, 1822, under the name of Cyclas 
partumeia. — [t is distributed all over the U. 8., 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 
color. The shell is rounded-oval, thin, fragile and pellucid ; nearly 
equilateral; beaks central, caly culate 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 cur ving behind, so as to form an obtuse 
angle, causing the posterior side to appear 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.) 
NuMerovs publications received will be noticed in our next 
number. 
