XVili. 
Rissoiidze. 
Rissoia, Frém., 1813. 
(type R. ventricosa, Desm.; an ally of 
BR. membranacea.) 
We prefer for the present to reserve our criticism of the sections of 
this group. 
Barleeia, Clark, 1855, 
(type) B. rubra, Mond. 
Paludestrinide. 
Paludestrina, D’Orb., 1840. 
The name Hydrobia having previously (as Hydrobius) been used in 
Coleoptera has been replaced by the above. The type of both genera is 
P. acuta, Drap. = P. ventresa, Mont. 
Bithinia, Gray, 1240. 
(type B. ventricosa, Gray = B. tentaculata, L.) 
Viviparide. 
Viviparus, Montf., 1810. 
(type) V. vivipara, ZL. 
Valvatidee. 
Valvata, O. F. Miill., 1774. 
(type) V. cristata, Midd. 
Assimineide, 
Assiminea (Leach), Fleming, 1828. 
(type) A. Grayana, Leach. 
Paludinella, Pfeiffer, 1841. 
P. littorina, D. Ch. 
Truncatellide. 
Truncatella, Risso, 1826. 
Proposed by Risso for the two forms 7. laevigata and T. costulata, both 
of which, as also 7. éruncatula, are synonyms of T. subcylindrica, L. 
