112 



one-third wider than high, if measured along the median line where the 

 emargination is deepest. 



Surface finely ribbed and marked by periodic arrests of growth. The 

 ribs are flexuoag and curve distiucily forwards, they are also acute and 

 much narrower than the concave grooves between them. Nearly all the 

 ribs are simple but occasionally one may be seen to bifurcate near the 

 umbilical margin, and there are very obscure ti-aces of still finer and 

 shorter secondary ribs intercalated between the larger one. The costar 

 tion, too, though certainly minute, is still rather plainly visible to the 

 naked eye. In each whorl there appear to be about four distinct arrests 

 of growth. These consist of rounded elevations, which are broader and 

 more prominent than any of the ribs, but which run almost exactly 

 .pai-allel with them, and which are as strongly marked on the cast as they 

 are on the shell. The ribs, on the contrary, are too minute to leave any 

 definite impressions on the cast. Septation unknown. 



Maximum diameter, seventeen lines and a-half; width of umbilicus, from 

 suture to suture, rather more than nine lines. 



Lower Conglomerates, Division C, of Norris Eock, a small " Island about 

 a mile S. 60° E. from Norman Point, which is the most southern part of 

 Hornby Island " ; J. Eichardson, 1871. A fragment only of the inner 

 whorls. 



Theabove description is not intended as a specific diagnosis, but merely 

 as a brief summary of the characters exhibited in the imperfect and im- 

 mature individual represented on Plate 13. The tj^pe of A. Jukesii (from 

 the Hard Chalk of the County of Londonderry, Ireland) is also a single 

 fragment of an Ammonite, in much the same condition as the present 

 shell, but which, Mr. Sharpc says, when perfect, probably measured five 

 or six inches in diameter. In the figures of this specimen the inner 

 .whorls appear to be more flattened at the sides than the corresponding 

 volutions of the Ammonite from Norris Eock ai-e, but at present no other 

 differences of any consequence can be pointed out between the two 

 shells. 



(Hamites Vancouverensis, Gabb. 

 Hamitks Vancouverensis, Gabb.— Pal. Cal., Vol. I., p. 70, pi. 13, fig. 18. 



" Vancouver Island, associated with Ammonites Newberryanus and other 

 Ammonites, species undetermined." — Gabb. Not recognised in any of 

 Mr. Eichardson's collections. A large epecies whose septation is un- 

 known, but which is characterized by its prominent, distant ribs, each 

 of which bears a tubercle "on the dorso-lateral angle." ) 



