470 THE LIAS AMMONITES. 



group, and resembles an elegant form of that species observed in the passage-beds 

 between the Amaltheus-spinatus and Step/tanoceras-commune zones in Dorsetshire. 



Locality and Stratigraphical Position. — Mr. Beesley collected his specimen at Adder- 

 bury. Mr. Edwin A. Walford collected those he kindly sent me for inspection from 

 Chipping Warden, Northamptonshire, where it is associated with Stephanoceras commune 

 and forms approaching Stephanoceras crassum. 



Harpoceras Normanianum, d'Orbigny. PI. LXXXIII, figs. 1, 2. 



Ammonites Normanianus, d'Orbigny. Paleontol. Francaise, Terr. Jurassiques,p. 291, 



pi. 88, 1842. 



Diagnosis. — Shell compressed, carinated, bisulcate, and slightly involute; whorls 

 compressed, convex in the middle, and flattened at the marginal and spiral sides, 

 regularly costated transversely, with upwards of seventy simple biflexed radii with nearly 

 equal sulci between. Siphonal area narrow ; carina prominent, having a narrow groove 

 on each side ; aperture quadrate, compressed on the sides, and roundly angulated. 



Dimensions. — Transverse diameter 85 millimetres ; width of umbilicus 40 millimetres ; 

 height of aperture 25 millimetres; width 17 millimetres. 



Description. — The Ammonite figured on Plate LXXXIII, figs. 1, 2, resembles Am. 

 Normanianus, d'Orb., more closely than any other that has passed through my hands. It 

 has the same number of simple costse equally biflexed, a like amount of involution, 

 but in addition it has two small lateral grooves on each side of the carina which are 

 absent in d'Orbigny 's type shell ; how far this may be a variable or persistent character is 

 unknown. 



Locality. — I found this specimen in one of the cases of the British Museum with the 

 MS. name I have retained ; the shell was numbered, but the locality from whence 

 it had been collected was not mentioned. Judging from the petrology of the matrix it 

 appears to be Middle Lias. 



The existence of the small, bell-shaped Aptychus in the body-chamber induced me to 

 have the specimen figured. 



