RISSOI1XE. 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 Rissoida? and Melaniidse ; in 

 1880 he classes the group as part of the latter. 



1. Baikalia stiedse. 



Leucosia Stiedse, Dyboivslci, Acad. Imp. St. Petersburg, 1875, Lake Baikal ; 

 sect. LiobaiJcalia. 



1 Lake Baikal; ex Mr. R. Damon, 



Genus TRACHYBAIKALIA, von Martens [emend.]. 



JaTirl. Mai. Ges. 187 6, for Ligea, DylowsTci, 1875, type T. costata, Dyb. [not 

 of Fabricius, genus Crust.'] ; sect. = GodlewsTcia, Crosse and Fischer, 

 J. de C. 1879, type T. turriformis, Dyb.; belongs to Fam. Melaniidce,fide 

 Clessin. 

 Not represented in the Museum. 



Subfamily SKENEIN^E, Stimpson. 



Genus SKENEA, Fleming. 

 Hist. Brit. Anim. 1828,-type Turbo planorbis, Fabr. 



l. Skenea planorbis. 



Turbo planorbis, O. Fabricius, Fauna Greenland, 1780. 



8 England ; coll. G. Nevill, Esq. 

 10 England ; ex Mr. R. Damon. 



Subfamily POMATIOPSIN^, Stimpson. 



Genus POMATIOPSIS, Tryon. 

 P. PJiilad. Ac. 1862, p. 452, type Paludina lapidaria, Say. 



1. Pomatiopsis lapidaria. 



Paludina lapidaria, Say, J. Ac. Nat. Sci. 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. J. Conch. I t 1865, S. E. Oregon. 

 4 Oregon ; coll. Prof. W. Newcomb. 



