310 ME. s. s. BVCKMAX OX [vol. Ixxiiiy 



Hwiccian-Wessexia n. — -The importance of the giant Acantho- 

 pleuroceras is that during considerable collection in the brickyards 

 of the Cheltenham district nothing at all approaching the size of 

 this specimen and of another fragment, Acantlwpleuroceras gigas 

 (Quenstedt j,i nearly as large, rewarded my efforts. These specimens 

 were found by the late Eev. Dr. F. Smithe, F.Gr.S., during the 

 making of the Banbury & Cheltenham Railway at Leckhampton ; 

 and the inference is that a stratum different from any of the brick- 

 yard exposm-es must have been cut through. Whether the stratum 

 belongs to any of the Acanthopleuroceras horizons discovered by 

 Mr. Lang on the Dorset Coast, or whether it is distinct from them 

 is a point towards which the attention of future workers should be 

 directed. 



The local distribution of AcantliopJeirroceras in the Cheltenham, 

 district seems to indicate two separate horizons, apart from the 

 horizon of the giant forms. Battledown near Cheltenham yields 

 mainly thin species ; Leckhampton Station near Cheltenham and 

 Hucclecote near Grloucester yield chiefly stout-whorled species. 

 Further -afield Northampton shire and Radstock yield the thin 

 species — solely, I think, more commonly at any rate. Hitherto 

 these Acanthojyleuroceras-jieldmg strata have been reckoned as 

 all in the same zone, but it is now evident that more investigation 

 is rec^uired. 



In the Cheltenham district a great variety of Acantliopleu- 

 rocerata are found, but rarely otherwise than as body- whorl 

 fragments, which makes their specific identification difficult. 



I cannot call to mind anything in literature of the size of 

 the large Acanthopleuroceras (260 mm.). Quenstedt's A. gigas 

 (pi. XXXV, fig. 14) I esthnate at about 170 mm. ; his ' largest 

 fragment ' (fig. 15) may go up to 200 mm. : the Leckhampton 

 fragment — a body- whorl — reaches 214 mm. in diameter, however. 

 Dumortier's Ammoniies jlandrini- measures 202 mm.; but this 

 is a species of quite a distinct t^'pe, special perhaps to the South of 

 France. Wiirtemberg, then, is the only area at all congi-uous with 

 Grloucestershire in regard to these large forms ; and it would seem, 

 if these large forms occupy a distinct horizon, that this horizon 

 has been preserved in areas limited and isolated geographicalh'-. 



Raasayan. — Deroceras hispinigerum marks a Deroceras hori- 

 zon below the main outbreak of Echiocerata. It is interesting as a 

 representative of the bituberciilate ancestor of the unituberculate 

 armaii, and shoAvs the obsolescence ot the inner row of tubercles. 



Deiran. — The species of JRadstockiceras and GJeviceras are 

 chosen as representatives of the faunas of the Radstock and 

 Gloucestershire Oxynotoid horizons, now separated from the oxyno- 

 fum horizon; but there are several other species in the latter area 



^ ' Ammoniten d. Schwabischen Jiira ' pi. xxxr, figs. 14 & 15. 

 - ' Bassin dii Rhone ' vol. iii (1869) pi. xiv. 



