﻿S P H iE R I U M. 



Genus SPH^RIIEVI. Scopoli. 



MOLLUSOUM ACEPHOLOPODUM, BIMUSCrLOSl'M, FLUVIATII, 

 SIPHONIBUS SEPAKATIS. Tcsia I'H il ,'.<, i nh''!< f,'H nil 



tcstiiceii, extn 



niea, wqu. 



Iilfrumqut^ injlata. Cardo 



"I"'- 



,i,-„t;i,„. 



iluiibiit! citrdinalibtis divenjentibus, lateraiibus 

 t'liiiigidt!', compressis, duplicatis et ghnplicihus. 

 I'allii iiiijjresslonibus iniegris. 



Mollusc acepholopodous, bi-mdsculapv, fluviatile, 

 WITH SEPARATED SIPHONS. Shell thin, thinly- 

 shelly within, horny without, equivalve, nearly 

 equilateral, generally inflated. Hinge in eacli 

 valve with two cardinal diverging teeth, lateral 

 teeth, two and one in each valve, elongated, com- 

 pressed. Palleal impression entire. 



Synonym. Cijdas. Brnguiere. 



The chief difference between this genus and 

 Pisidinm is to be found in the siphons of the animal, 

 which are divided in the former, and separated in 

 the latter. The shells, however, are in general to be 

 distinguished by those of the present genus being 

 less oblique, and more equilateral. Wherever there 

 are rivers and lakes, are also to be found shells of the 

 Sjjhreriam genus, excepting, perhaps, in the towid 

 regions. They abound in Europe and North 

 America. The British Museum, largely reinforced 

 by the Cumingian Collection, presents a large an-ay 

 of species which are given in this monograph, besides 

 others which are accessible to me ; still, however, 

 leaving some which cannot be got together for iden- 

 tification. 



Species 1. (Mus. Brit.) 



SPHJiRinM Steinbdchii. Sjih. testd parvd, politd, sub- 

 obliqiin, semipelliicidd, pallidd; latere postico 

 obliqiir prudncln, tuargine dorsali declivi ; latere 

 iiiit.'r,: l,i,iiii^i:ido; umbotiibus prominentibus, 

 rvrxii.-: Inhrrm untieuin indinatis. 



Steinbuch's Sph.erium. Shell small, polished, rather 

 obliqne, semipellucid, pale ; posterior side ob- 

 liquely produced, dorsal margin sloped ; anterior 



side rather short; umboes prominent, leaning 



towards the anterior side. 

 MiiLLEB. Adams. Geneva. 

 Uiih. Greenland. 



Species 2. (Mus. Brit.) 



Sph^riuji TRANsvEKSUiM. Sph. testd transverse ovatn, 

 p(dlide cnrtied, tenui, (ipacd, umbonihiis ovaiif, 

 sidicriifrtdibiis, margine dorsali rediilscnlo ; latere 

 antiai breviascnlo, margl.iiibus laleralibiui suJi- 

 truncatis, margine ventrali convexo. 



The transverse Sph«rium. Shell transvei-sely ovate, 

 pale horn, thin, opaque, umboes ovate, subcentral, 

 dorsal margin rather straight ; anterior side 

 rather shorter, posterior lateral margin, a little 

 obliquely truncated, ventral margin convex. 



Sat. Proc. Acad. Nat. Sci. Phil. 180-2. 



Uab. United States. 



3. (Mus. Brit.) 



Sph.sridm rivalis. Spli. testa rediiisculd, sulaqni- 

 laterali, iiiflatd, transversa, corned, fiiseo-subvirldi, 

 fasciatd; umbonibus ovatis, magiiis; margino 

 re>drali redo, laterihus siibtruiicatis. 



The river Sph^erium. Shell rather straight, nearly 

 equilateral, inflated, transverse, horny, banded 

 w ith greenish brown ; umboes oval, large ; 

 ventral margin straight, sides rather truncated. 



Drap. Moll. PL X. 



Uab. Europe. 



Generallyregardedas a variety of S^/i(e;-i((Hiconie«/;(, 

 but more transverse aud rhomboidal. 



Species 4. (Mus. Sowerby.) 



SPttSEiUM RiviCOLUM. Sph. testd iiMgiid, oratd, 

 tenidter sulcata, intense fuscu-virldi, intih nudin 

 carneold, versus marginem cwruled ; umbotiihii.t 

 subcentral ib us, obtusis, margine darsali idrinqite 

 declivi. 



The river-dwelling Sphj;riu5I. Shell lar^^e, oval, 



