Vol. 52.] A DELIMITATION OP THE CENOMANIAN. 155 



d'Orbigny, a common Cenomanian shell, as a synonym of this species. 

 It is certainly not the true Tr. spinosa of Parkinson, and, having 

 compared a specimen from the Chloritic Marl of Havre with 

 d'Orbigny's figure of Tr. spinosa and with examples of Tr. Vicar y ana 

 from Devon, we believe them to be identical. Tr. Vicaryana is 

 therefore a common shell on both sides of the Channel. 



Cephalopoda. 



Ammonites complanatus, Mant. See Sharpe, ' Chalk Mollusca ' 

 Pal. Soc. Monogr. p. 19, pi. vii. figs. 1-3. —A. Largilliertianus, 

 d'Orb., ' Pal. Fr. Terr. Cret.' pi. xcv. 



Having found a specimen of this rare shell in a fallen mass of 

 Bed 11 on Pinhay beach, west of Lyme Regis, it is interesting to 

 observe that Sharpe identifies it with A. Largilliertianus, which has 

 been found in the Cenomanian of Eouen, and also in that of the 

 Sarthe, according to M. Guillier (' Geologie de la Sarthe,' 1886). 

 Mi Guillier apparently considers the two forms to be distinct 

 species, for he enters both of them in his list. The original English 

 specimen was found in the Chalk Marl of Hamsey, near Lewes. 



Ammonites euomphalus, Sharpe, ' Chalk Mollusca,' p. 31, pi. xiii. 

 fig. 4. 



This is another very rare ammonite, of which only one specimen 

 was known to Mr. Sharpe, obtained from the base of the Chalk in 

 Man of War Cove, Dorset. Our specimen was found in the sandy 

 chalk, Bed 13 of Mr. Meyer, in the cliff below Whitlands coast 

 guard station, west of Lyme Regis. 



Ammonites Gotjpiliantts, d'Orb., ' Pal. Fr. Terr. Cret.' vol. iii. p. 317, 

 pi. xciv. figs. 1-3 ; and Sharpe, ' Chalk Mollusca,' p. 38, pi. xvii. 

 figs. 5&6. 



This is a sharply-keeled ammonite, with faintly-marked sigmoid 

 ribs, resembling A. varians in form, but distinguished by its suture. 

 Mr. Meyer has found one specimen in Bed 13 below Whitlands. 

 Mr. Sharpe had only seen one obtained from the ' Grey Chalk ' 

 of Hamsey (? Chalk Marl). It has not been found in the Cenoma- 

 nien of Western France, but occurs in beds of Turonian age at 

 Saumur on the Loire. 



Ammonites laticlavius, Sharpe, ' Chalk Moll.' p. 31, pi. xiv. fig. 1. 

 This form was only known to Sharpe from the Chloritic Marl of 

 the Isle of Wight, but it has since been found in the upper part of 

 the Lower Chalk of Yorkshire (see Quart. Journ. Geol. Soc. 

 vol. xliv. 1888, p. 351). Dr. Barrois has found it to be not un- 

 common in the zone which he calls by its name in the North-east of 

 France, and which appears to be equivalent to our Chloritic Marl. 

 In Devon, Mr. Meyer has found a specimen in Bed 11. 



