181 



Elk Island, Lake Winnipeg, T. C. Weston, 1884, abundant; also Deer 

 Island, T. C. Weston, 1884, one specimen, and J. B. Tyrrell, 1889, one 

 specimen. 



MOLLUSC A. 



PELECYPODA. 



Pal^opteria. (Gen. nov.) 



Shell small, aviculoid in outline, both ears being well developed and 

 the left valve more convex than the right : hinge dentition consisting of 

 minute elongated thin laminar teeth, nearly parallel with and close to 

 the cardinal margin, on both sides of the beaks. 



The specimens upon which this genus is based are all casts of the 

 interior of separate valves, and the slightly divergent hinge teeth are re- 

 presented by their imprints, which are scarcely visible to the naked eye. 

 When carefully examined with a lens, however, these casts show the 

 impressions of two anterior and two posterior teeth in the right valve, 

 and of two anterior and apparently three posterior teeth in the left valve. 

 The genus is here proposed at the suggestion of Mr. Ulrich, who has 

 examined the specimens, and who thinks that their hinge dentition is 

 more like that of the Macrodontidse than any pterineoid hinge known to 

 him. 



Pal^opteeia parvula. (N. Sp.) 



Plate 20, figs. 1, 2 and 3. 



Shell inequilateral, oblique, with a small anterior wing and a larger 

 and more obtusely angular posterior alation, and varing in outline from 

 obliquely or elongated subovate to somewhat rhomboidal. Anterior side 

 shorter than the posterior : anterior end, inclusive of the wing, longest at 

 the hinge line, rather acutely subangular above, narrowing obliquely 

 inward and sometimes a little concave at the midheight, and ultimately 

 curving convexly, obliquely and abruptly, inward and downward, to the 

 ventral margin below : posterior end, also inclusive of the alation, obtusely 

 angular at its junction with the cardinal margin above, obliquely trun- 

 cated and slightly concave at about the midheight, narrowly rounded and 

 somewhat produced below : ventral margin broadly rounded : cardinal 

 margin long and straight : beaks incurved, elevated slightly above the 

 hinge line, and placed a little in advance of the midlength. 



Surface markings unknown, though on some of the specimens there 

 are a few concentric plications preserved, which are most distinct 

 anteriorly. 



