WHiTEAVEs.] FOSSILS OP TRIASSIC ROCKS OF BRITISH COLUMBIA. 143 



one of which is placed on the umbilical margin, six next to it, one at 

 the junction of the side with the periphery, and one, which appears to 

 be divided into two points, next to the abdominal groove. 



The sutural line consists of three lateral saddles on each side of the 

 siphonal saddle, and of two principal lateral lobes, besides a third and 

 minute lobe, which is partly sunk in the umbilical cavity, on each side 

 of the siphonal lobe. The margins of all the saddles are rounded and 

 entire, but those of the lobes appear to be minutely incised. The 

 siphonal saddle is much smaller than'any of the rest; the first and sec- 

 ond lateral saddles are nearlj^ equal in size and a little larger than the 

 third. The siphonal lobe, whose summit is shallowly emarginate in 

 the centre by the small siphonal saddle, is a little larger than the first 

 lateral lobe, and it again is slightly larger than the second lateral. 



Dimensions of the only specimen collected : greatest diameter, fifty 

 millimetres; maximum breadth or thickness, twenty mm.; greatest 

 breadth of umbilicus, thii'teen mm. 



Liard Eiver, about twenty-five miles below Devil's Portage, E. G. 

 McConnell, 188*7 : one tolerably well preserved and nearly perfect cast 

 of the interior of the shell. 



According to Professor Hyatt, this specimen belongs to the group of 

 the Trachycerata margaritosa of Mqjsisovics. "It is closely allied to 

 Trachyceras Aon, Mojs. (Ceph. der Med. Triaspr., p. 133, pi. 21, figs. 

 1-38), but differs therefrom in the number of rows of closely arranged 

 tubercles, in its broad abdomen and the division of the spines of the 

 abdomen into two points. It is like P. ladinum, Mojs. (lb., pi. 14, 

 fig. 2), but has more rows of tubercles, and these smaller ; also like T. 

 Judicaricum, Mojs. (lb., pi. 14, fig. 3), but is more involute. It is also 

 like T. longobardicum (lb , pi. 19, fig. 4), but is different in the sutures 

 and has smaller ribs and tubercles." 



In the writer's judgment the specimen now under consideration 

 appears to be still more closely related to the Nevada fossil which has 

 been referred to T. Judicaricum in the fourth volume of the United 

 States Geological Exploration of the Fortieth Parallel, on the author- 

 ity of Professor Hyatt, who, however, now doubts the correctness of 

 this identification, as will be seen from the following extract from a 

 letter of his to the present writer, dated March 20th, 1888 :— " At the 

 time that I wrote the note for Meek in Geol. Bxpl. 40ch Parallel, vol. 

 iv, p. 118, I was disposed to give greater latitude to specific characters 

 than I am now. I should not, I think, now consider the shell there 

 described as T. Judicaricum. If Meek's figures are at all correct, the 

 nodes and pilse (ribs) are distinct, as are also the involution and chan- 

 nel. Your specimen, if I remember rightly, differed from Meek's in 

 having very much finer pilffi (ribs), many rows of closely set tubercles. 



