386 Mr. Jeffreys on the Testaceous Pneumonobranchous 



rinatus in his Einleilung to the Helix complanata of Linnaeus, 

 he has not separated the other two. His fig. 13. PI. V. of the 

 Flussconchylien is an exact representation of the P/. lutes- 

 cens ; and in speaking of his " Helix planorbis crassa" (our 

 PL umbilicatus), he says, " The specimen from Hamburgh is 

 black, with the keel sharp and visible on both sides. 



Much confusion existed in Miiller's time as to the Helix 

 Planorbis and complanata of Linnaeus ; nor has it been in 

 any wise removed by succeeding authors. In their eager- 

 ness to adapt their new discoveries to the pages of that 

 illustrious naturalist, they seem to have lost sight of the 

 circumstances under which even the latest edition of the 

 Systema Natura was written, and to have given him credit 

 for trivial distinctions, which it was scarcely possible could, 

 in that state of science, have been attended to, and which 

 often they themselves but imperfectly understood. The 

 Helix Planorbis of that work has been referred by the three 

 authors who have last treated on the subject of British Con- 

 chology, to as many distinct species ; and nearly as great 

 uncertainty has prevailed as to the true H. complanata. 



8. Draparnaldi. 

 Animal 



Testa utrinque subumbilicata, perforata, caring medid sub- 

 prominul4, lateribus aequalibus, tenuis, pellucida, gla- 

 bra (sub lente transversim argutissim^ striata), lutes- 

 centi-fusca. Anfr actus 5, convexiores. Apertura dila- 

 tata, subrotundo-rhomboidea : peristomio libero. 



Long. 0.1. — Diam. 0.325. 



Planorbis spirorbis. Drap. Hist, des Moll. p. 45. t. 2. 



/. 8, 9? 



Planorbis 



