WHiTEAVEs.] FOSSILS OF TRIASSIC ROOKS OF BRITISH COLUMBIA. 141 



Aroestes G-abbi, Meek. 



Ammonites Ausseanus, Gabb.— 1864. PalEeont. Californ., vol. I., p. 25, pi. 3, figs. 



11 and 17 (not of Hauer, teste Meek). 

 Arcesten Gahhi, Meek.— 1877. U.S. Geol. Expl. 40th Parallel, vol. IV, pt. I, p. 121, 

 pi. 10, figs. 6, 6 a and 6 b. 



Bay five miles and a half west of Cape Commerell, north end of 

 Vancouver Island, G. M. Davrson, 1885: one tolerably perfect specimen 

 and a few fragments of others. 



A nearly perfect but considerably crushed and distorted specimen of 

 an Arcestes, collected by Dr. Dawson in 1818 at Houston Stewart Chan- 

 nel, in the Queen Charlotte Islands, has been referred to this species 

 bv the writer, in the Eeport of Progress of the Geological Survey of 

 Canada for ISYS-^O, but its specific relations are somewhat doubtful. 



ACROOHORDICERAS (?) CaRLOTTENSE. (N. Sp.) 



Plate 19, fig. I. 



The foregoing name is suggested provisionally for a remarkably 

 sculptui-ed shell, of which two rathej- large fragments, which Professor 

 Hyatt thinks are "probably specimens of Acrochordiceras,'' were 

 collected by Dr. Dawson in 18*78 at Houston Stewart Channel, Q.C 1. 



The larger of these two fragments is a piece of the outer volution 

 about twenty-seven millimetres high in its dorso-ventral diameter, 

 about thirty-five mm. in length from the posterior to the anterior 

 termination and twelve mm. in thickness near the periphery. 



The outer volution seems to have been strongly compressed at the 

 sides, the umbilicus appears to have been narrow and in both speci- 

 mens the periphery or abdominal region is distinctly flattened. At 

 and near the posterior termination of each of these fragments, the ribs 

 or pilsB are frequently bifurcating and in one instance bidichotomous, 

 but in their anterior halves the ribs are broken up into numerous, short 

 and simple, transversely elongated tubercles. 



These specimens, Professor Hyatt writes, " are interesting in so far 

 as they exhibit a style of sculpturing which is ditferent from that of 

 any Triassic form I have ever seen either upon a specimen or figured. 

 They both at an earlier stage evidently had divided pite, but these at 

 the stage of growth represented in both these fragments have begun 

 to be resolved into numerous, short and elongated, interrupted folds. 

 The style of this makes the larger of the two fragments a close copy 



