255 



fresh-water shells : twenty or more may sometimes 

 be seen attached to their sides like thin threads. 



The eggs are similar to those of PlanorMs and 

 Limruzus, in groups forming oblong or rather depressed 

 globular masses, attached to the surface of leaves. ( See 

 Pfeiffer, t. 8. f. 1 8. ; see also Jeffreys, Linn. Trans. 

 xvi. 380.) 



5. APLEXUS Fleming. (Aplexus.) 

 Animal exactly like Physa, but the mantle edge is 

 simple and not reflected over the shell, and the 

 tentacles are without any auricle at the base ; the 

 shell is longer, and the inner lip is parallel to the 

 outer, and not spread over the body whorl. 



Adanson first described this genus in 1757, under 

 the name of Bulin (Bulinus), which ought to be 

 adopted ; but it would create confusion, as Hartmann 

 and Mr. Broderip have lately changed Lamarck's 

 genus Bulimus, which is synonymous with Cochlea of 

 Adanson, into Bulinus. 



99. I. APLEXUS hypnorum. Slender Aplexus. (t. 9* 

 f. 1 13.) Shell horn-colour, oblong, with an elong- 

 ate pointed spire ; aperture oval-lanceolate. 



Physa hypnorum. Drap. p. 55. t. 3. f. 12, 13.; 

 Turton, Man. ed. 1. 129. f. 113. 



Limnea turrita. Soicerby, Gen. f. 10. 



Bulla hypnorum. Linn. S. N. i. 1185.; Mont. p. 

 228. 



Nauta hypnorum. Leach, Mollusc, p. 152. 



Planorbis turritus. Mutter, Verm. ii. 169. 



In ponds and slow streams. 



Animal blackish ; foot quite as long as the shell ; 

 tentacles black. 



