1921 



TUL1TIDM 



47 



with a slight backward curve, then come forward to sweep with a very 

 slight forward arching over venter ; no sign of smooth stage, nor of 

 costal degeneration, in the two species examined, but there is the 

 beginning of umbilical expansion. England, Dorset. 



Sphaeroconic shape, and ribs with regular sweep, not angulate, 

 good distinctions from Rugiferites. 



P. pleurophorus, n. A costate sphaerocone, without any sign of 

 umbilical expansion. S.B., ex J.B., Coll. 1919 ; Genotype and Holotype ; 

 Troll, near Thornford, Dorset ; Fullers' Earth Rock (Thornford Beds — 

 a rather soft bed, with a slight pinkish tinge, and also some suggestion 

 of bluish argillaceous matrix) ; S. 56, 45, 82, 23 ? ; 74, 42, 82, 22 ; size 

 c. 95, not suitable for measurement, as the specimen is an allomorph ; 

 about 35 primary and 75 secondary ribs ; max. c. 105. 



P. polypleurus, n. A sphaerocone commencing serpenticone by 

 slight umbilical expansion, but without any sign of costal degeneration. 

 About 32 primary ribs produce about 85 secondary — junction obscure, 

 partly due to preservation, partly to intercalation. S.B., ex J.B., 

 Coll. 1927, Holotype ; Troll, near Thornford, Dorset ; Fullers' Earth Rock, 

 (Thornford Beds — a stratum similar to that of P. pleurophorus, perhaps 

 harder, not so much sign of argillaceous resting place) ; S. 60, 41, 69, 

 25 ; 92, 40, 55, 27 ; max. c. 105. 



BULLATIMORPHITES, g. n. Genotype, Ammonites bullatus ; 

 Lycett, 1863, (non d'Orbigny), Moll. Great Ool., Suppl., p. 4 ; PI. xxxi, 

 f. 1 ; cf. Am. bullatus] latecentratus, Quenstedt ; Amm. Schwab. J., II, 

 p. 658 ; PI. lxxvii, 6. Sphaeroconic passing to serpenticonic by excen- 

 trumbilication ; costae (at first approximate, then somewhat distant, 

 later approximate again) of low relief, often trifurcate, some sign of 

 angularity of Rugiferites pattern in the distant stage, later more regular 

 curve, radial ; mouth-border laterally contracted with good forward 

 sweep ; immediately before border a fairly marked constriction in cast 

 [not shown if test present ?] ; s.l. incomplete, simple ? England, 

 Gloucestershire; (Germany, Swabia ?).  



The genus is nearest to Pleurophorites, but is distinguished by its 

 mode of coiling. 



B. bullatimorphus, n. Am. bullatus; Lycett, cit. Geol. Surv. 

 Engl., ex Lycett Coll., 25620, Holotype and Genotype ; " near Tiltups 

 Inn, two miles south of Nailsworth, [Gloucestershire] ; Great Oolite " 

 (Lycett, p. 4), from a whitish, weathering ochre, hard, crystalline, lime- 

 stone, feebly oolitic, but many oolite grains (?) show in cast of body- 

 chamber ; test thin, preserved on inner whorls and part of outer ; S. 100, 

 48. 53+. 19; 179, 34. 33. 39; max. 183; s.l., only indications; body- 

 chamber 1 \ whorls ; no sign of any smooth stage. 



B. latecentratus Quenstedt sp. (Am. bullatus latecentratus, Quen. 

 1887, lxxvii, 6). This appears to be a smaller edition of B. bullati- 

 morphus ; " Laufen, [Wiirtemberg] ; Brauner Jura t." 



Morrisceras, S. Buckman, 1920, (Legend of PL CLXVII, 

 T.A. Ill) ; Genotype, Morrisiceras sphcera, S.B., Holotype = Macro- 

 cephalites morrisi, Auctt. Cadicones which pass to incipient platycones 

 through a sphaerocone stage. [Primary ribs not developed into knobs, 

 bifurcating into rather strong secondaries in cadicone stage] and becoming 

 obsolete ; sphaerocone stage characterized by secondary ribs only, 

 crossing venter with a slight forward curve, and strongest in middle of 

 venter ; [they disappear in incipient platycone stage, when complete 

 smoothness supervenes, correlated with excentrumbilication and whorl- 

 reduction. S.l. simple, lobes short and broad, Li about 38 per cent, of 



