Ill 



Island shell just mentioned, the outer Avhorl is entirely smooth, and in the 

 previous volution to that, the ribbing- is almost obsolete. The sculpture 

 of half-grown examples of J.. Newherryanus, the condition in which it is 

 most frequently met with, is subject to much variation, and the single row 

 of nodes around the umbilicus on both sides, which Mr. Meek seems to 

 regai"d as one of the most marked peculiarities of the species, is often 

 absent. 



It is just possible that A. Newberry anus may be only a geographical 

 variety of A. planulatiis Sowerby, for the septation of the two shells is 

 very similar, the whorls of both are flattened at the sides, and each have 

 about the same number of periodical arrests of growth. The main points 

 in which they differ are that all the ribs of A. planulatiis become obsolete 

 before reaching the umbilicus, which is certainly not the case in A. 

 Newberryartus, and that in A. planulatus the ribs arch forwards on the peri- 

 phery, whereas they are straight in the same region in A. Neioberryanus. 

 The umbilicus of A. planulatus is generally wider in propo'rlion to the 

 shell, than is that of -4. Newberryanus, but Stoliczka figures an Indian 

 specimen of A. plannlaius in which the umbilicus is not any wider than it 

 is in Vancouver examples of .4. Neioberryanus of the same size. 



Group 6. — Fimhriati, D'Orbigny. 



Sub-genus Lytoceras, Suess. — Sitzungsberichte der K. K. Akad. der Wissenschaften. 



Vienna, 1865. 



Ammonites Jukesii ? Sharpe. 



riate 13, figures 3, 3a and 3b. 



Ammonites Jukesii. ? Sharpe. — Description of the Fossil Remains of MoHusca found in 



the Chalk of England, p. 53, pi. 23, figs. 11, a to e. 

 « " " Pictet and Campiche. Pal. Suisse, Foss. de Ste Croix. 



Page 350. 



Shell composed of numerous slightly involute rounded whorls ; um- 

 bilicus large and open ; surface finely costulate and marked with distant, 

 nearly transverse but flexuous elevations, the remains of former lips. 



Whorls seven or eight, rounded, but widest near the umbilical margin 

 and narrowing a little towards the periphery; dorso- ventral diameter of 

 the whorls, outside of their shallow internal emargination, rather less 

 than the greatest width of their sides. Umbilicus wide, its mai'gin and 

 sides abruptly rounded ; measured from suture to suture its width is rather 

 more than half the maximum diameter of the shell; sides of the whorls 

 fully exposed ; sutures distinct. Aperture transversely reniform, fully 



