CYCLAS. 115 



There is a subglobose variety (apparently the stagnicola 

 of Mr. Sheppard) which is flattened towards the ventral 

 margin, and has the pellucid and swollen umbones pecu- 

 liarly prominent. 



The dimensions of the larger typical form are six lines 

 and a quarter in length, and five lines in breadth ; of the 

 variety, five lines and a half in length, and four and three- 

 quarters in breadth. 



The animal is white, its subelongated siphonal tubes 

 tinted with pale flesh-colour. Mr. Jenyns observes, that 

 the superior tube is subconic, with a small aperture, the 

 inferior cylindric and truncate, with a wider aperture. Mr. 

 Glover notes on the variety Jfavescens, " from running water, 

 under stones," that its animal is straw-coloured. 



For " this very common species, a general inhabitant of 

 rivers, ponds, and ditches throughout the country, which 

 appears to thrive equally well both in running and in stag- 

 nant water 11 (Jenyns), we do not cite any particular locali- 

 ties, reserving the space thus gained for less thoroughly 

 investigated species. 



Cyclas cornea is generally distributed throughout Europe, 

 and occurs fossil in freshwater strata of the Pleiocene age 

 in the valley of the Thames. 



C. caliculata, Draparnaud. 



Shape more or less rhombic ; umbones narrow, more or less 

 prominent, capped. 



Plate XXXVII. fig. 7 (as lacustris), and (animal) pi. 0, fig. 7. 

 Cyclas caliculata, Draparn. Moll. Ter. et Fluv. France, p. 130, pi. 10, f. ] 4, 

 15.— Turt. Manual L. and F. W. Shells, p. 1 4, pi. 1, f. 3.— 

 Brown, Illust. Conch. G. B. p. 94, pi. 39, f. 28.— Lam. 

 Anim. s. Vert. (ed. Desh.) vol. vi. p. 269. — Pfeiff. Deutsch. 

 Land und Siissw. Moll. pt. 1, p. 122, pi. 5, f. 17, 18.— 

 Nilsson, Moll. T. et Fl. Sueciae, p. 99. — Kickx, Moll. 

 Brabant, p. 89. — Desh. Encycl. Meth. Vers, vol. ii. pt. 2, 



