Ammonites halecis ; suckman, 1844. 
CEPHALOPODA Ammonites halecis 
J. Buckman, 1844. 
Original description 
(1844. — Op. cit., pp. 104 and 90). 
« A. halecis, Tab. 11, f. 9. — Keel slight, volutions 4 or 5, exposed, ribs rather distant, 
sharp, curving forwards, with a sharp angle, across the dorsum of the shell where the ribs 
become united to the keel; at the angle of the curve, there is a slight prominence hardly 
amounting to a tubercule : this, and the bend of the ribs flat across the back, makes this 
Ammonite broadest posteriorly. Diameter 1 1/4 in., thickness 1/2 in., aperture one-half. » 
« LocaLrTy. — Lias Shales, Railway cuttings, etc. » 
[P. 90.] « L. S. Vale of Gloucester. » 
OBSERVATIONS 
The above description, which is on the whole satisfactory, may be supplemented thus : 
— The somewhat distant, somewhat coarse ribs run straight across the lateral area, and bend 
forwards slightly on the periphery to join the keel, so that the ribs on the periphery form a 
broadly expanded À. The « aperture one-half » is incorrect ; it is rather more than a third 
of the diameter. 
The generic position of the species may be thus indicated : — It is closely related to 4. 
Sauxeanus, d'Orb. and 4m. Gaudryi, Reynès, and somewhat less allied to Am. Scipionianus, 
d'Orb., and Am. Colesi, J. Buckm. The first two species Hyatt placed in his second subseries 
of the genus Coroniceras (Gen. Arietidæ, 1889. Smiths. Contrib., No 673) ; while he put 
Am. Scipionianus in the genus Agassiceras, subsequently making it however, the type of a 
genus Aetomoceras (1900. — Eastman-Zittel, Text-Book of Palæont., p. 575). S. S. Buckman 
(Geol. Mag., Dec. IV., vol. I, 1894, p. 361), suggested the placing of all these species in the 
genus Agassiceras, perhaps more correctely to be written Agassizoceras. 
Locality and Horizon. The information given with the type may be thus interpreted : 
Lower Lias, Sinemurian (zone of Am. obtusus ?) cuttings on the Midland Railway in the 
neighbourhood of Cheltenham, Gloucestershire. 
1904. S. S. Buchman. 
26° 
