252 CYCLAD.2E. 



ropods, they contrive to traverse the vessel from 

 side to side, as though they were crawling along a 

 solid plane. 



1. CYCLAS Lam. (Cycle.) 



Animal with suborbicular mantle produced behind 

 into two elongate contractile siphons; foot 

 tongue-shaped, very extensile; shell suborbi- 

 cular, nearly equilateral ; hind teeth minute, one 

 in the right and two in the left valve ; lateral 

 teeth compressed, elongate, lamellar. 

 The shells are known from Pisidium by their being 

 rounder and more equilateral. 



a. Cardinal teeth two, diverging, well developed ; shell 

 rounded, and not channelled at the umbones. 



114. 1. CYCLAS rivicola. River Cycle. Shell sub- 

 globose-ovate, ventricose, rather solid, beauti- 

 fully and closely striated, greenish brown, 

 with two or three darker bands; edge and 

 lunule yellow ; umbones obtuse ; cardinal 

 ligament conspicuous, (t. 1. f. 1.) 



Tellina cornea, (3. Maton and Racket, Linn. Trans, viii. 59. ; 



Turton, Conch. Diet. 180.; Wood, t. 46. f. 3. Cyclas 



cornea, a. Drop. Tabl. Cardium corneum, var. Montagu, 



T. B. 86. Cyclas cornea, a. Drop. Hi*t. Moll. 128. t. 10. 



f. 1. 3. Cardium aranicum. Dorset. Cat. 32. Cyclas rivicola. 



Leach, in Lam. hist. v. 558.; Pfeiffer, L. and W. 121. t. 5. 



f. 3. 5.; Turton, Bivalves, 248. t. 11. f. 13.; Fleming, Brit. 



Anim. 452. ; Jenyns, Trans. Comb. P. S. 6. ; Turton, Man. 



ed. 1. 12. f. 1.; Leach, Syn. Moll. 289. ; Dupuy, Moll. Franc. 



665. t. 29. f. 3.; Forbes and Hanley, B. M. ii. 111. t. 37. 



f. 12. t. 2. f. 1. Sphaerium riviculum. Mont. Cat. ii. 30. 



Sph. rivicola. Bourg. in Amden, 6. 1. ; Bourg. Mon. 12. 

 Young, compressed, pale. 

 Cyclas aequata. Sheppard, MSS. Brit. Mus. 



Inhab. rivers Thames, Trent, &c. 



