Mollusca of Great Britain. 387 



Planorbis deformis. Lam. Hist, des Anim. sans Vert. 6. 



p. 154. 

 Helix rhombea. Turtons Conch. Diet. ? 

 Draparnaudi. Shepp. in Linn. Trans. 14. p. 158. 



Sparingly among the rejectamenta of the river Taaf 

 near Cardiff. It somewhat resembles an over-grown spe- 

 cimen of the following ; but differs in the disproportionate 

 size and medial carina of the last volution, and, above all, 

 in its colour and fine transverse striae. 



9- Albus. 



Animal grisescens. Tentacula longa, flexilia. 



Testa utrinque subumbilicata, perforata, tenuis, pellucida, 



reticulato-striata, albida, epidermide fusco induta. 



Anfractus 5, convexiores. Apertura subrotundo-rhom- 



boidea : peristomio vix soluto. 



Long. 0.075. — Diam. 0.2. 



Planorbis albus. Miill. Verm. 2. p. l64. 



hispidus. Drap. Hist, des Moll. p. 43. t. 1. 



y.45 — 18. Lam. Hist.des Anim.sansVert.Q. p.l54i. 

 Helix spirorbis. Linn. Syst. Nat. 1. p. 1244. 

 alba. Gmel. Syst. Nat. 1. p. 3625. Mont. Test. 



Brit. p. 459. t.25.f. 7- 



Common on aquatic plants in ditches and slowly-running 

 streams. The term " souvent hispide," applied by Dra- 

 parnaud to this shell, may perhaps have originated in an 

 accidental erosion of the epidermis. 



10, Glaber. 



Animal 



Testa supra planior, subtiis umbilicata, utrinque perfo- 

 rata. 



