138 CONTRIBUTIONS TO CANADIAN PAI-^ONTOLOGY. 



fliiltened, but probably abnormally so: sides and umbilical margin 

 both rounded, the latter not at all angular: aperture a little more than 

 twice as broad as high, transversely subreniform, or transverselj' and 

 bi-oadly elliptical but shallowly emarginate in the centre ot the base 

 by the encroachment of the preceding volution. 



Septa somewhat closely approximated, their average distance apart 

 on the periphery, where their margins are nearly straight, being 

 about six millimetres. Position of the siphuncle unknown. 



Surface apparently almost smooth, and marked only by transverse 

 striffi of growth. 



Dimensions of the only specimen collected : maximum length, 

 fifty-seven millimetres; maximum breadth at the aperture, where the 

 shell is broadest, fifty-eight mm. ; height of aperture in the centre, 

 twenty-seven mm. 



Liard Eivor, about twenty-five miles below Devil's Portage, R, G. 

 McConnell, 1887: a slightly distorted cast of the interior of the shell, 

 with small portions of the test preserved, hut with the greater poi'tion 

 of the chamber of habitation broken off. The number of septa 

 whose margins are visible in this specimen is twenty-one, and the por- 

 tion of the body chamber that remains is about three-quarters of an 

 inch in length. 



This shell appears to bear such a close resemblance to the Nautilus 

 Slbyllce of Mojsisovics,* from the Trias of Spitz;bergon, in almost every 

 respect, that it may possibly prove to be only a local variety of that 

 species. Still, in the figures of JV. Sihyllce the umbilical margin is rop- 

 I'csented as i-ather distinctly angular, whereas that of N. Liardensis is 

 very regularly rounded. 



POPANOCERAS MoCONNELLI. (N. Sp.) 



Plate 18, figs. 2, 2 a, b, and 3, 3 a. 



Typical Form. (Figs. 2 and 2 a, b.) Shell glohosely sublenticular, but 

 always a little depi'essed in the umbilical region : greatest thickness or 

 breadth varying in different specimens Irom a little more to a little less 

 than half of the maximum diameter : umbilicus well defined and rather 

 deep, with steep sides, but very narrow and rather less than one-eighth 

 of the maximum diameter, in adult specimens. At a very early stage of 

 growth, however, the umbilicus is much wider proportionately. Thus, 



* Arktisohe Triasfaunen (Mem. I'Ac Imp. des Sciences de St. Pt^tersbourg, Ser. VII, Vol. 33 

 No. 6), p. 100, pi. 16, fig. 2. 



