British species of Cyclas and Pisidium. 295 



Cyclas rivicola, Leach MSS. — Lam. An. sans Verteb. 5. 558. — Pfeiff. 

 Land-mid Wasserschn. 121. t. 5. f. 3-5. — Turt. Conchyl. Brit. 248. 

 t. 11. /. IS.— Turt. Man. of Brit. Land and Freshw. Shells. 12. 

 / 1. — Flem. Brit. An. 452. 



Tellina cornea /3, Mat. and Rack. Linn. Trans. 8. 59 Turt. Conch. 



Diet. 180. 



Cyclas cornea, Draparn. Hist, des Moll. 128. t. 10. f 1 — 3. — Brard, 



Hist, des Coq. 219. t. 8. f 2. 3. 

 Jun. C. asquata, Shepp. 3ISS. Brit. Mus. 



Animal mihi ignotum. 



Testa globosa, subovalis, ventricosa, solidiuscula, eleganter et distincte 

 striata ; fusco-virescens, fasciis 2 — 3 saturatioribus, margine basali 

 luteo; intus casrulescens : umbones tumidi, pallidiores, linea nigricante 

 plerumque cirenmscripti : margo dorsalis antice lunula, postice fissura 

 distincte impressa, utraque flavescenti : ligamentum cardinale con- 

 spicuum. 



This species is at once distinguished from the next, and from all 

 the other British ones of this family by the superior size of the shell : 

 the animal I have not seen. It appears to be confined to rivers, and is 

 found I believe abundantly in the Thames, as well as in some other 

 parts of the country. The largest specimens in my possession are from 

 the Trent in Nottinghamshire. In its young state, it appears to be 

 identical with the C. eequata of the Rev. R. Sheppard, according to 

 specimens so named by that gentleman in the British Museum. 



Sp. 2. C. cornea, Lamark. 



C. testa suborbiculari, globosa, tenerrime striata ; umbonibus obtusis ; 

 ligamento cardinali inconpicuo. 



Long. 6% lin. Alt. 5. lin. Crass. 4 lin. 



