186 GENESIS OF THE ARIETIDA. 
Var. Gaudryi. 
Plate VI. Fig. 14. Plate VIII. Figs. 1-3. 
Cor. multicostatum, Hyatt, Bull. Mus, Comp. Zodl., I., No. 5, p. 78. 
Amm. Gaudryi, Reynts, Plates. 
Ariet. Sauzeanus, Wriaut, Lias Amm., Pal. Soc., pl. viii. fig. 1-6. 
On the sixth volution this shell has slightly convergent sides, a thick, low 
keel with shallow broad channels. The pil are tuberculated, and the geniculse 
bending forward break up the channel ridges into a series of waves. They also 
pass over the umbilical shoulder on the dorsal side, but are not so prominent 
there. The very rapid increase in size of the whorl renders the umbilicus about 
half an inch deep at the end of the sixth volution. On third quarter of the fifth 
whorl the channels are very faint, the genicule where they ascend upon the 
abdomen are less prominent, and tubercles much higher up on the edge of the 
abdomen. If the pila were less prominent and devoid of abdominal extensions, 
this stage would precisely represent the usual form of var. Sawzeanum. 
On the fifth and sixth whorls the abdominal lobe is about two fifths longer 
than the superior laterals, and the inferior lateral saddles exceed the superior 
laterals in the same proportion. 
The German specimens are precisely like the English. One in Quenstedt’s 
collection from Betzenrieth bei Géppingen is identical with the English specimen 
of the same age. Wright’s figures all belong to var. Gaudryz, and exhibit a well 
defined keel and convergent sides at an early age. 
Coroniceras bisuleatum, Hyarr. 
Plate VII. Fig. 2-10. Summ, PI. XII. Fig. 11. 
Amm. bisulcatus, Brue., Encycl. Meth., I. p. 39, pl. xiii, 
Amm. bisulcatus, D’Orz., Terr. Jurass. Ceph., p. 187, pl. xliii. 
Cor. bisulcatum, Hyarr, Bull. Mus. Comp. Zodol., I, No. 5, p. 77. 
Ariet. rotiformis, Wrieu'r, Lias Amm., p. 278, pl. ix. (not pl. v., vii.). 
Amm. multicostatus, Sow., V. p. 76, pl. ecccliv. 
Amm. multicostatus, HAvgR, Ceph. Nordostl. Alpen, pl. i. fig. 3, 4. 
Ariet. subnodosus, Wricut, Lias Amm., p. 288, pl. vi. fig. 2, 3. 
Amm. resurgens? Dum., Etudes Pal. Bassin du Rhone, pt. 2, pl. xxiii. fig. 3-6. 
Amm. milticostatus, Zret., Verst. Wiirt., pl. xxvi. fig. 3. 
Localities. —Lyme Regis, Semur, Hechingen, Balingen. 
There are four specimens of this species, two from Semur, one from Hech- 
ingen, and one from Balingen, which differ in a significant manner. Both of those 
from Semur have a somewhat closer resemblance to the full grown Cor. Sauzea- 
num than the German specimens;. they differ, however, in some respects. On 
one, the pile are visible on the last quarter of the sixth whorl, and show on the 
cast distinct traces of tubercles, and the genicule terminate before they reach 
the channel ridges, which are continuous and entire. In the other specimen, the 
pile are visible on the first quarter of the seventh whorl, do not show on the cast 
distinct traces of tubercles, and the genicule pass over the channel ridges as in 
Sauzeanum. In both German specimens the channel ridges have a crenulated 
