FEOM THE DISTEICT OF ATHABASCA. 117 



small portiou of each of the inner whorls is exposed in the umbilicixs, but in D. Alha- 

 bascense the inner whorls are completely covered by the overlapping of the outer A'olution. 

 The exterior of the septate portion of the shell of the typical form of D. affine, also, is 

 marked with varix-like periodic arrests of growth, and the outer surface of the body 

 chamber of both it and its var. glabrmn by low, distant and feebly developed ribs, whereas 

 the outer volution of D. Allnibascense is apparently smooth posteriorly, and marked only 

 with from two to three broad, faint and almost obsolete transverse constrictions on the 

 outer portiou of the body chamber. 



Family STEPHANOCEKATID^ (Neumayr) Zittel. 



Hoplites McConnelli. (Sp. nov.) 



Plate XI., figs. 2, 2 a-b. 



Shell small, discoidal, sides compressed, periphery narrowly rounded : umbilicus 

 occupying more than one-fourth and less than one-third of the total diameter, and expos- 

 ing about one-third of each of the inner volutions, but with its margin rounded and iil- 

 defined : aperture elongated, higher than broad, subelliptical in outline, but shallowly 

 emarginated posteriorly by the encroachment of the preceding volution. 



Surface marked by feebly developed, simple and flexuons radiating ribs, which 

 become almost obsolete on the periphery, with finer striœ between them. By the use of 

 a lens, also, several minute spiral striœ can be detected on the sides of the outer volution. 



Suturai line consisting of three lateral saddles and two lateral lobes on each side of 

 the siphoual saddle and lobe, besides two or three minute saddles and lobes on the inner 

 face of the umbilicus. Siphonal saddle very short and incised only at the summit : first 

 lateral saddle much larger thau the second, its summit divided very unequally into two 

 short primary branches, which are subdivided, the outer and larger one into three still 

 shorter and incised secoadary brauchlets, and the inner and smaller one into two : second 

 lateral saddle larger than the third, its summit also divided unequally and somewhat 

 similarly, but with the larger of its primary branches on the inner side : third lateral 

 saddle divided unequally at the summit, with the larger of its two lobate branches on 

 the outer side. Siphonal lobe a little shorter than the first lateral lobe, symmetrical and 

 bearing three incised and spur-like processes on each side : first lateral lobe trifurcate above 

 and divided into three branchlets, which are slightly expanded and deeply incised at their 

 summits : second lateral saddle small, its summit expanded and perhaps better described 

 as unequally bifurcate than as trifurcate. 



Maximum diameter of the largest specimen collected, the one figured, nearly forty 

 millimetres, or a little over an inch and a half. 



Clearwater Shales of the Athabasca River, at the Burnt Rapids, R. Gr. McConnell, 

 1890 : two small septate specimens, with most of the test well preserved. 



This small Ammonite appears to belong to the group Flexuosi of von Buch, as limited 

 by Pictet in the first volume of the Paléontologie Suisse, and to be most closely related 

 to the Ammonites Caslellanensis of d'Orbigny. It is probably a rather aberrant member of 

 that section of the genus Hoplites which Zittel designates as the group of Ammonites 

 cryptoceras, d'Orbigny. 



