4{4 PROCEEDINGS OE THE ACADEMY OF 



clas sulcata and Cyclas Saratogea. Say, in 1819, ignorant that this shell 

 was known to conchologists, described it as the Cyclas s i m i 1 i s, under which 

 name, until very recently, it has been most generally known. Say also fig- 

 ured this species, but his figure, I regret to say, is not correct, and would be 

 more apt to give one the idea of a Pisidium than of a Spha?rium. The descrip- 

 tion by Say of the Cyclas s i m i 1 i s applies perfectly to the shell under con- 

 sideration, of which Dr. Gould has given a very good figure in his Report on the 

 Invertebrata of Massachusetts. 



As related elsewhere,* I had an opportunity, some years since, while in 

 Paris, to see Lamarck's original specimens of the Cyclas sulcata and Sara- 

 togea, at the Garden of Plants, and at the Delessert Museum; and to con- 

 vince myself by examination that they both belonged to one species, and were 

 identical with Say's Cyclas s i m i 1 i s. 



2. Sph. aureum, Prime. 



Cyclas aure.ua, Prime, Boston Proc. iv. 159, 1851, 



Animal, not observed. 



Shell transversely oval, slightly elongated, nearly equilateral, heavy, con- 

 vex ; beaks full, raised above the outline of the shell ; anterior margin broad 

 and rounded; posterior narrower and somewhat angular; inferior slightly 

 curved ; hinge margin somewhat broad, curved ; cardinal teeth diminutive, 

 double, so placed together as to represent the form of the letter V reversed, 

 and rather wide-spread ; lateral teeth situated each one at an angle with the 

 cardinal teeth, strong and large ; sulcations deep, not very regular ; epidermis 

 varying from a greenish yellow to a bright gold color, slightly lustrous ; inte- 

 rior of the valves bluish white. 



Long. 9-16 ; lat. 7-16 ; diam. 6-16 inches. 

 Hab. North America, from Lake Superior ? 

 (Cabinet. Agassiz and Prime.) 



This is one of our most attractive species, but also one of the rarest. It is 

 supposed to have been brought from Lake Superior by the expedition which 

 visited that region under Professor Agassiz. Iu general outline it offers some 

 similarities with the Sph. sulcatum; it is, however, a much more ponderous 

 shell ; it is less elongated, more convex, its sulcations are not so regular, its 

 color is different, and lastly, its hinge margin is much more curved. 



Compared to the Sph. solidulum, it is more convex, more elongated, its 

 posterior margin is broader, the hinge margin is not so much curved, the beaks 

 are fuller, and the sulcations are not quite so heavy ; the color is also dif- 

 ferent. 



3. Sph. s olid ul um, Prime. 



Cyclas solidula, Prime, Bost. Proc. iv. 158, 1851. 

 C. distorta, Prime, loc. sub. cit. iv. 158, 1851. 



Animal, not observed. 



Shell transversely inequilateral, elongated, slightly convex ; beaks full, not 

 very prominent ; anterior margin rounded ; posterior drawn out to an angle ; 

 base slightly curved ; epidermis variable, dark chestnut or brownish yellow, 

 with sometimes a yellow zone on the basal margin ; sulcations coarse, irregu- 

 lar ; interior dark blue ; hinge margin considerably curved ; cardinal teeth 

 double, in the shape of the letter V leversed ; lateral teeth large ; the anterior 

 placed at an angle with the margin ; the posterior more on a continuation of 

 the curve. 



Long. 9-16 ; lat. 7-16 ; diam. 5-16 inches. 



* N .trs on some American species of Cyclas, etc., by Temple Prime. The Hague, 

 1857. 8vo. 



[Dec. 



