XVii. 
Cecide. 
Ceeum, Fleming, 1817. 
(type) C. trachea, Mont. 
C. glabrum, Mont, 
Littorinide. 
Littorina, Fér., 1821, 
(type) L. littorea, LZ. 
L. rudis, Maton. 
L. neritoides, ZL. 
L. obtusata, L. 
For the last name it appears advisable to use Neritoides, Brown, as a 
sub-genus. 
Lacuna, J'urton, 1827. 
(type) L. puteolus, Z'urton. 
L. divaricata, Fabr. 
L. pallidula, Da Costa. 
L. crassior, Mont. 
Homalogyride. 
Homalogyra, Jeff., 1867. 
H. atomus, Philippi. 
H. rota, Forbes and Hanley. 
Skeneidee. 
Skenea, Fleming, 1828. 
(first species S. depressa, Moné. = 8. planorbis, Fubr.) 
S. planorbis, Fabr. 
Adeorbiide. 
Adeorbis, S. V. Wood, 1842. 
A. subearinatus, Mont. 
Jeffreysiide. 
Jeffreysia, Alder, 1849. 
(type) J. diaphana, Alder. 
J. opalina, Jef. 
J. globularis, Jef. 
