186 GENESIS OF THE AKIETIDiE. 



Var. Gaudryi. 



Plate VI. Fig. 14. Plate VIII. Figs. 1-3. 



Cor. multicoslalum, Hyatt, Bull. Mus. Comp. Zool., I., No. 5, p. 78. 



Amm. Gaudryi, Rkyne's, Plates. 



Ariet. Sauzeanus, Wkight, Lias Amm., Pal. Soc, pi. viii. fig. 1-6. 



On the sixth volution this shell has slightly convergent sides, a thick, low 

 keel with shallow broad channels. The pilae are tuberculated, and the genicular 

 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 genicular where they ascend upon the 

 abdomen are less prominent, and tubercles much higher up on the edge of the 

 abdomen. If the pilae were less prominent and devoid of abdominal extensions, 

 this stage would precisely represent the usual form of var. Saitseanum. 



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 Goppingen is identical with the English specimen 

 of the same age. Wright's figures all belong to var. Gaudryi, and exhibit a well 

 defined keel and convergent sides at an early age. 



Coroniceras bisulcatum, Hyatt. 



Plate VII. Fig. 2-10. Summ. PI. XII. Fig. 11. 



Amm. bisulcatus, Brug., Encycl. Meth., I. p. 39, pi. xiii. 



Amm. bisulcatus, D'Orb., Terr. Jurass. Ceph., p. 187, pi. xliii. 



Cor. bisulcatuM, Hyatt, Bull. Mus. Comp. Zool., I, No. 5, p. 77. 



Ariet. rotiformis, Wright, Lias Amm., p. 278, pi. ix. (not pi. v., vii.). 



Amm. multicostalus, Sow., V. p. 76, pi. ccccliv. 



Amm. multicostalus, Hauer, Ceph. Nordostl. Alpen, pi. i. fig. 3, 4. 



Ariet. subnodosus, Wright, Lias Amm., p. 288, pi. vi. fig. 2, 3. 



Amm. resurgens"> Dum., Etudes Pal. Bassin du Rhone, pt. 2, pi. xxiii. fig. 3-6. 



Amm. multicostalus, Ziet., Verst. Wiirt., pi. 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 pilae are visible on the last quarter of the sixth whorl, and show on the 

 cast distinct traces of tubercles, and the genicular terminate before they reach 

 the channel ridges, which are continuous and entire. In the other specimen, the 

 pilae are visible on the first quarter of the seventh whorl, do not show on the cast 

 distinct traces of tubercles, and the geniculae pass over the channel ridges as in 

 Sauzecmimi. In both German specimens the channel ridges have a crenulated 



