part 4] JURASSIC cheois^ology : lias^ 289 



Genus GrLEYiCEEAS,^ nov. 

 Type, G. glevense, nov. (para type). 



Definition. — -Involute, septicarinate suboxycone, passing to 

 less involute, non- septicarinate platycone — the periphery broaden- 

 ing, carina declining (passing to rounded, uncarinate ?), whorls 

 inflating. Ribs subregular, simple. Radial line laterally nearly 

 straight with distinct forward projection, less in stage of 'rib- 

 decline. Suture-line somewhat complex — no long branches from 

 the external lobe, one accessory lobule in the external saddle, 

 superior lateral lobe rather long, narrow-stemmed, but declining to 

 broad-stemmed later. 



Distinction. — From Oxyiioficeras, the suture-line is more 

 developed, but the oxyconic character is much less developed, — 

 return towards platycone commencing before anything like the 

 knife-edge periphery of OxijuoticerciB is attained. From ^ad- 

 stockiceras, with a lower stage of involution and a rather less 

 developed periphery this genus combines a less complicated suture- 

 line. From Agassizoceras, of which at one time I thought it 

 might be an involute development, a suture-line too much deve- 

 loped. See also another character below, p. 292. 



Remarks. — The A''arious species which a]3pear to belong to this 

 genus are those cited in the Comparative Table. Ammonites 

 guibnlianus D'Orbigny and A. victoris Dumortier must be ex- 

 cluded for various reasons. See below, p. 293. 



GrLEVICERAS G-LEVEXSE, nom. nov. (PI. XXVII, figs. 2 & 3 ; 

 PI. XXVIII, figs. 1 & 2 ; PL XXIX, fig. 3 ; PI. XXX, fig. J. ; 

 text-figs. 4 & 5, p. 294; 11, 20, p. 295.) 



184i. Ammonites greenlioughii J. Huckmaii, 'Geol. Chelt.' new ed. p. 89. 



1881. Amalthetvs giiibcdianus Wright, ' Mon. Lias Amm.' pi. xlv, figs. 6& 7 only. 



1904. Agassizoceras greennughi S. Uuckman [nan Sowerby) in L. Ricliardson, 



' Handbook of the Geology of Cheltenham ' p. 212. 

 Cf. 1879. Ammonites gtiihali Keynes {nan guibaliaiiics D'Ovhigny), ' Mon. Amm.' 



pi. xlvi, fig. 13 oiih'. 



General details. ^ — Whorls broad (inner margin rounded), 

 inclusion nearly to the inner edge of the preceding whorl up to 

 128 mm. diameter, in another ^ whorl (not preserved) umbilical 

 expansion rapid, inclusion only about ^. Periphery sloping ogival, 

 with raised hollow keel up to about 86 mm. diameter, in another 

 half-whorl keel small, hollow character obsolescent, periphery 

 flattening but narrower than dorsum, in another half-whorl peri- 

 j^her}^ flatly ogival, almost as broad as dorsum, carina almost 

 obsolete. Ribs indistinct, undulate, occasionally bifurcate on the 

 outer margin : they tend to become irregularly obsolete at or after 

 145 mm. diameter, when irregular swellings (old-age rugosities) 

 appear. 



[Final stage (not preserved), smooth (or irregularly^ swollen) 

 with rounded uncarinate periphery and excentrumbilication ?] 



^ Glevum, the Roman name for GloiTcester. 

 q. J. G. S. No. 292. 2 a . 



