18 TYPE AMMONITES— III June 



1920 



Galeatiform, becoming sphaeroconic ; periphery 2 ; ornament 4, 

 obscurely bullate on S 1 ; versiradii, towards periphery rursiradii with 

 little peripheral projection. S.L., lobes long, rather narrow, L a about 

 to guide-line. 



A massive galeatiform series in which the most inflated species, 

 G. goliathus, attains to a swollen stage of about 100 per cent. Has 

 usually been assigned to Cardioceras, but whorl-shape, inflation, radial 

 line and suture-line are all distinctive. Radial line has little projection 

 on periphery, it crosses a feeble keel by a broad V ; most of its lateral 

 portion lies beyond guide-line. Many species rising to G. goliathus and 

 then declining. [Lobes not so long in declining species— septal degenera- 

 tion ?] England, France ; Argovian 5. 



Pavloviceras, g. n. Genoholotype P. pavlovi, R. Douville sp., 

 a specimen in Mr. Tutcher's Coll. which agrees with Qitenstedticeras 

 pavlovi, R. Douv., Cardioc. Mem. Soc. G. Fr., xlv, 1912, 74, 75, XI (v), 13. 

 Sphsroconic ; periphery 1; ornament 4, coarse and bullate, OV L a , 

 ribs rounded — funiculate — rursiradiate, very slight V on middle of 

 venter. S.L., lobes rather long and somewhat narrow, L l not as long 

 as E L, L 2 about same distance from guide-line as L*. 



Like Goliathiceras in inflation and suture-line, but differing in the 

 more massive ornament and in the fact that the attempt towards a keel 

 fails very early — it would only be found in brephomorphs and anamorphs 

 — so that a flatly arched venter is produced. 



Normandy ; England (Dorset, Oxfordshire, Huntingdonshire) ; 

 Swiss Jura ; Russia. Divesian, vertnmnus, according to Douville's 

 Normandy evidence ; but it is not yet known from Yorkshire. 



P. omphaloides, J. Sowerby sp. 1819 (M.C. Ill, 74, ccxlii, 5. 

 Whorls tumid, galeatiform, a little more than half-included. Ribs 

 about radial, sometimes a little rursiradiate — the primary and forward 

 secondary run nearly straight round whorl — the hinder secondary is 

 rursiradiate. The V on periphery is feeble. There is an attempt at 

 an angulate periphery and towards a knotted keel in youth, but this 

 faiis at about 25 mm. diameter. 



The above description is drawn up from a topotype. At the next 

 rib after' 34 mm. diameter this shows a sudden jump in the size of the 

 whorl — see proportions below. This explains a feature of Sowerby's 

 plate — there the sudden jump is shown at the second primary (fifth 

 secondary) rib from the end, before the pyritized lump — the same place 

 as in the topotype. In the next species, P. bathyomphalum, the jump 

 is shown about the same place — perhaps a rib earlier. Weymouth, 

 Dorset ; Oxford Clay, pyritized ; Mus. Geol. Surv. England, No. 30569 ; 

 S. 26, 42, 57, 31 ; 34.5, 41, 57, 29 ; 36, 47, 60, 29. Another example, 

 Oxfordshire ; same Coll. No. 30574, 26 mm. diam. 



P. bathyomphalum, nov. Cf. Quenstedticeras sutherlandice ; 

 Loriol, Pal. Suisse, XXVII, 1900, m, 10. Stouter than P. omphaloides, 

 with a smaller umbilicus, which, on account of stout whorls, is quite 

 deep. Periphery arched. Jump in size of whorl at about 34 mm. diam. 

 St. Ives, Hunts ; Mr. Tutcher's Coll., S. 26, 44, 67, 27 ; 34, 46, 70, 26 ; 

 50, 45, 65 ? 24 ; full size of specimen 59 mm. ; max. c. 90 mm. A brepho- 

 morph, Great Northern Railway [Walton, Hunts], Mus. Geol. Surv. 

 Engl. No. 30571, S. 20, 45, 60 ? 31— certainly thicker and less umbilicate 

 than P. omphaloides at the same diameter. 



P. stibarum, nov. Cf. Cardioceras goliathus ; Loriol, Pal., Suisse, 

 XXV, 1898, 11, 14. Stouter than P. bathyomphalum, with more flatly- 

 arched periphery, but less stout than P. pavlovi, and with less flattened 

 periphery. Ornament not so coarse as P. pavlovi, more in agreement 



