RISSOIDE. 63 
Clessin, in the Nachrichtsblatt for 1878, p. 126, considers 
Lartetia, Bourguignat, as a close ally, and that both should 
constitute a family between the Rissoide and Melaniide; in 
1880 he classes the group as part of the latter. 
1. Baikalia stiede. 
Leucosia Stieda, Dybowski, Acad, Imp. St. Petersburg, 1875, Lake Baikal ; 
sect, Liobaikalia, 
1 Lake Baikal; ex Mr. R. Damon, 
Genus TRACHYBAIKALIA, von Martens [emend.}. 
Jahrb. Mal. Ges. 1876, for Ligea, Dybowski, 1875, type T. costata, Dyb. [not 
of Fabricius, genus Crust.]; sect. = Godlewskia, Crosse and Fischer, 
J. de C. 1879, type T. turriformis, Dyb. ; belongs to Fam, Melaniide, fide 
Clessin. 
Not represented in the Museum. 
Subfamily SKENHINZ, Stimpson. 
Genus SKENEA, Fleming. 
Hist. Brit. Anim, 1828, type Turbo planorbis, Fabr. 
1. Skenea planorbis. 
Turbo planorbis, O. Fabricius, Fauna Greenland, 1780. 
8 England ; coll. G. Nevill, Esq. 
10 England; ex Mr. R. Damon. 
Subfamily POMATIOPSINZ, Stimpson. 
Genus POMATIOPSIS, Tryon. 
P. Philad. Ac. 1862, p. 452, type Paludina lapidaria, Say. 
1. Pomatiopsis lapidaria. 
Paludina lapidaria, Say, J. Ac. Nat. Set. I, 1817, Missouri to Michigan, 
18 Niagara Falls; coll. Prof. E. C. Stearns. 
12 Michigan ; coll. Prof. W. Newcomb. 
2. Pomatiopsis intermedia. 
Pomatiopsis intermedia, Tryon, Am. di, Conch. I, 1865, 8S. EB. Oregon. 
4 Oregon; coll. Prof. W. Newcomb. 
