36 CONTRIBITTIONS TO CANADIAN PALAEONTOLOGY. 



placed immediately under the jDOsterior termination of the hinge ancJ 

 their outer margins close to and parallel with the upper margin of the- 

 posterior ends of the valves. Anterior muscular soars about half as- 

 large as the posterior, and narrowly elongated in nearly the same- 

 direction, pointed above and below, broadly convex on their outer and 

 straight on their inner sides, placed high up in and partly across the 

 angles formed bj^ the hinge-line and the anterior margins. 



Belly Eiver, west of the mouth of the St. Mary Eiver, G. M. Dawson, 

 1881 : and Belly Eiver, near the mouth of the St. Mary Eiver, E. G-. 

 McConnell, ISs'l . St. Mary Eiver, near the Police Fort, T. C. Weston, 

 1883: South Saskatchewan, opposite Swift Current Creek, E. G-. 

 McConnell, 1882 and 1884. Lome Crossing of the Eed Deer Eiver^ 

 Township 35, Eange 16, west of 4th Principal Meridian : and Berry 

 Creek, Section 31, Township 25, Eange 12, wcbt of 4th Principal 

 Meridian, J. B. Tyrrell, 1884. One or two moi-e or less perfect but 

 usually very large sijecimens from each of these localities. 



This variety, if indeed it be sufficiently well marked to be called a 

 variety, appears to differ chiefly from the type of the species in its 

 much larger size and in the proportionately greater length of its pos- 

 terior wing. One of the sj)ecimens collected by Mr. Tyrrell on th& 

 Eed Deer Eiver, which is five and a half inches in length, apart from 

 the greater proportionate length of its posterior alation, is so like- 

 Meek's figure of G. recta that it can scarcely be separated from that 

 species even as a variety. It is not improbable that Meek's types of 

 G. recta are immature shells and that the specimens from the Cana- 

 dian Xorth-West, which are very characteristic of the Fort Pierre 

 Group of that region, may represent merely the adult form of the 

 species. 



3I0DI0LA ATTENUATA, Meek and Hayden. 



Mijiilus ottcnvoivs, :Meek and Hayden. Is5ii. Proo. Ac. Nat. Se. Phil., vol. A'lII.. 



p. 86. 

 Modiola attmuatu, Meek and Hayden. 1860. lb., vol. XII., p. 427. 

 VoUdla atknvaki, :ileek. 1876. Kep. U.S. Geol. Surv. Terr., vol. IX., p. 74, pi. 28. 



figs. 8a, b. 



St. Mary Eiver, near its confluence with the Bellv Eiver, T. C. Wes- 

 ton, 1883 : abundant. Three miles noi-th of Eoss Coulee, near Irvine 

 Station on the Canadian Pacific Eailway, T. C. "Weston 1884. 



