FEOM THE DISTRICT OF ATHABASCA. 113 



ance -with the classification of tlie Ammouoidea in the second volume of Zittel's " Hand- 

 buch der Palœontoloffie." 



-'o^ 



Family HAPLOCERATIDJÎ, Zittel. 



Desmoceras affine. (Sp. nov.) 

 Plate VIII., and PI. XL, figs. 1 and 1 a. 



Shell discoidal, sides strongly compressed, periphery very narrowly rounded, umbi- 

 licus so narrow that little more than the inner faces of the inner volutions are exposed, 

 its margin rounded and consequently ill-defined : aperture elongated in the dorso ventral 

 direction, narrowly subelliptical in outline, but deeply emarginate posteriorly by the 

 encroachment of the preceding volution. 



Surface, of septate specimens from two or two and a half to a little over four inches in 

 their maximum diameter, marked by very numerous and closely disposed, fine and 

 flexuous raised lines, which radiate obliquely outward and forward from the umbilical 

 margin to and across the periphery, also with distant periodic arrests of growth, each of 

 which consists of a narrow groove bounded anteriorly by a swelling rim. Upon the 

 chamber of habitation of adult or nearly adult specimens the surface markings consist of 

 distant, narrow and not very prominent or feebly developed, simple radiating ribs, with 

 broad but shallowly concave intervals between them. 



Sutures of the septa essentially similar to those of Desmoceras Beiidanti, the Ammonites 

 Beudanii of Bronguiart, as described and figured by d'Orbigny, Pictet and Campiche, 

 Stoliczka, and other palseontologists. 



Peace Eiver Sandstones on the Peace River, — twenty-two and five miles below the 

 Battle River, also twenty-five miles above that river, — and twenty-five miles below 

 Cadolte's River, R. G. McConnell, 1889 : one or two good specimens from each of these 

 localities. Loon River Shales on the Loon River (a tributary of the Peace), opposite 

 Buffalo Head Hills (four specimens), at the lower end of these hills (three specimens), 

 and thirty miles above its mouth (two specimens) ; R. Ci. McConnell, 1889. Loon River 

 Shales on the Red River ' (another tributary of the Peace), at the Second Rapids, R. Gr. 

 McConnell : six specimens. 



Clearwater Shale of the Athabasca River, at the Boiler Rapids, R. Gr. McConnell, 

 1890 : a badly preserved portion of the outer volution of a rather large specimen. 



Altogether, twenty-four specimens were collected, the largest of which is about ten 

 inches in its maximum diameter. These are remarkably similar to Desmoceras Beudanti, 

 in their suturai lines, sculpture and general shape, but they are invariably more closely 

 coiled and consequently more narrowly umbilicated. According to Stoliczka, scarcely 

 one-third of the inner whorls are exposed in the umbilicus of D. Beudanti, but in that of 

 the present species little more than their inner faces are exposed. Pictet and Stoliczka 

 represent the umbilicus of D. Beudanti as truncated on its inner face, with a rectangular 



' As there are two Red Rivers in the District of Athabasca it may be well to state that the one here referred 

 to takes its rise in the Birch Mountains, and flowing westward, empties into the Peace, about five miles below 

 Vermilion Falls. 



Sec. IV., 1892. 15. 



