O AMNICOLA. 



allied to the terrestrial ? genus Nematura, Ben- 

 son;* and, as far as the shell is concerned, it 

 has also some affinity with Fleming's sestuary 

 genus Cingula. It will probably be found to be 

 identical with Hydrobia, Hartmann, if the Palu- 

 dina thermalis be a proper example of it.t If 

 the characters of Paludina parvula, Guilding, 

 Zoological Journal iii. 537, pi. supp. 28, figs. 1 

 and 2,J are constant, it is possibly distinct from 

 Amnicola; the foot being lengthened triangular, 

 and the left tentacle twice the length of right 

 one. 



It is difficult to separate the bare shells having 

 a circular aperture, from Valvata and Cyclos- 

 toma, and it is possible that porata may belong 

 to the former, and one or two of the others to 

 the latter genus. 



* Vide Sowerby's paper in Charlesworth's Mag. Nat. 

 Hist. i. 217. 



f This European species is distinct from all those de- 

 scribed herein. Among some notes made in 1840, but not 

 since verified, I find that the foot and antennae are furnish- 

 ed with vibrillae, which are interspersed with erect hairs 

 upon the latter organs, the length of the vibrillae being 

 about 0.01 millemeter; the hairs a little more. About 8 

 rows of pectinated branchiae were observed. 



^ Copied in Swainson's Malacology (Cab. Cyc.) p. 198. 



