116 
THE NAUTILUS. 
15, alt. at aperture 7 } mm. Specimens from East branch of Salmon 
brook, Woodland, Aroostook Co., Me., coll, by O. A. Nylander, 
Caribou, Maine. 
Vivipara georgiana limnothauma n. var. 
Whorls much swollen around the upper part, sloping helow, giv¬ 
ing a shouldered appearance. This is one of the most remarkable 
forms of Vivipara yet made known. Types are from an aboriginal 
shell-field on Hitchen’s Creek, but it also occurs living in Lake 
George, 2 fms., off Drayton’s Island (Pilsbry and Johnson coll.). 
MOLLUSKS OF ALLEGHENY CO., PENNSYLVANIA. 
BY GEO. H. CLAPP, PITTSBURGH, PA. 
Below is given a list of additional species of land and fresh-water 
shells collected in Allegheny Co., Pa., to be added to the list pub¬ 
lished by Mr. S. H. Stupakoff in the Nautilus, April, 1894. 
Hyalin a cellarius Miill. 
Hyalina nitidus Miill. 
Mesodon mitchelliana Lea. 
Pupa curvidens Gld. 
Succinea aurea Lea. 
Succinea obliqua Say. 
Limnsea parva Lea. 
Gvraulus dilatatus Gld. 
Pleurocera canaliculatum Say. 
Goniobasis ? (Young). 
Unio ovatus Say. 
Unio rectus Lam. 
Unio pilaris Lea. 
Unio crassidens Lam. 
Unio luteolus Lam. 
Unio gracilis Lam. 
Unio rubiginosus Lea. 
Unio orbiculatus Hild. 
Unio securis Lea. 
Unio cornutus Bar. 
Unio undulatus Bar. (?) dead 
[broken shell. 
Unio obliquus Lam. 
Ancylus tardus Say. 
Ancylus rivularis Say. 
From the previous list, Alesomphix Icevigatus Pfr. should be drop¬ 
ped. I have found Mesodon sayii Binn. in Beaver Co., but have 
not, so far, found it in this county. 
NOTE ON UNIO OREG3NENSES LEA. 
For years I have been puzzled over a shell in the Lea collection 
of Naiads which Lea received from Wheatley as coming from the 
