1908] ■ Chazy Pelrcypoda 111 



Modiolopsis Nats, Billings, from the Black River limestone at 

 Paquettes Rapids, but is flatter and distinctly though shallowly 

 depressed in front of the posterior umbonal slope. It looks 

 as if it had been abnormally compressed. 



The type specimen of M. fabcejormis is in }.ir. Raymond's 

 collection. 



Orthodesma AXTiguu.M, sp. nov. 



Plate III, fig. 10. 



Shell somewhat compressed, most convex and prominent' 

 on the posterior umbonal slope of each valve; slender, elongated, 

 and nearly four times as long as high. 



Anterior portion of the valves verv short and narrowly 

 rounded; posterior portion of the same more than five times 

 as long as the anterior, a little higher and deeper behind the 

 midlength than in front of it; superior border or dorsal margin 

 increasing slowly in height posteriori v, nearlv straight, but 

 slightly convex ; its inferior border or ventral margin also 

 nearly straight, but faintly concave; posterior extremity rrther 

 obliquely subtruncated, and apparently forming a subangular 

 and somewhat pointed junction with the ventral margin. Beaks 

 small, inconspicuous and appressed, placed at a short distance 

 from the anterior end. 



Test unknown; surface of casts marked with concentric 

 lines of growth. In one specimen these growth lines are rather 

 numerous and closely disposed. Hinge dentition unknown; 

 muscular impressions indistinctly defined. 



Five badly preserved and for the most part ver}- imperfect 

 casts of the interior of single valves. 



This species occurs also in the Chazv sandstone at Aylmer, 

 where specimens have been quite recently collected bv Mr. 

 T. W. E. Sowter, associated with Whitella Canadensis. It 

 is provisionally referred to Orthodesma on account of its re- 

 semblance, in marginal outline, to certain well known species, 

 such as O. rectum. Hall and Whitfield, and O. suhnasntum 

 (Meek and Worthen). If it is an Orthodesma, it is the oldest 

 known species of that genus. 



Vanuxemia pakvula, sp. nov. 



Plate III, figs. 11 and 12. 



Shell small for the genus, valves moderatelv con\-ex, broadly 

 subovate, or ovately subtrigonal, and very little longer than 

 high. 



