U.' 



YORKSHIRE TYPE AMMONITES-II Dec 



Genus, PSEUDOCADOCERAS, nov. 



Type, Am. hngavus, Bean, Syntype=P. boreale, Y.T A. CXXI b 



Svn. (Jioceras pars, Auctt. The Gme>m^-senes, S. Buckman, 1913, 162. 



Cadoceratid series like young Cadoceras, but not developing 

 cadicone stage, only feeble inflation: the catagenetic feature of excen- 

 tnimbilkation, commencing almost as soon as swelling, would prevent 

 any cadicone development. [Suture-line (d'Orbigny, 1848, clxxix, 9) 

 rather simple, L* same length as EL, L 2 short and broad]. 



Genus, LONG^EVICERAS, nov. 

 Type, Am. longavus, Bean, Lectotype, Y.T. A. CXXI a 

 A Cadoceratid series like Pseudocadoceras but prorsiradiate, attaining 

 only to feeble swollen stage. Develops oxycone ? 



R. Douville (1912, p. 21) reckoned Am. galdrynus as a Chamoussetia, 

 but its lack of inflation indicates a different stock. It is an involute 

 development either of present genus or of a parallel series ; for this one 

 may end without developing keel. Am. funiferus, Phillips, 1829, vi, 23, 

 is prior name for Am. galdrynus. 



Genus, EBORACICERAS, nov. 

 Type, A. dissimilis, Brown, Holotype, Y.T. A. CXVIII a 

 A Cadocerated series which develops considerable inflation but does 

 not attain to cadicone. Versi-, subflexiradiate, ribs of low relief, primaries 

 short, secondaries angulate on periphery, but straightening out in swollen 

 stage ; obsolescence follows. L l rather narrow-stemmed, longer than EL, 

 L 2 quite short, rather broad (cf. d'Orbigny, clxxvi, 3). Eboracum, 

 York. 



Genus, PRORSICERAS, nov. 

 Type, Am. gregarius, Leckenby, Lectotype, Y.T. A. CXVII a 



A Cadoceratid series swelling in serpenticone stage, presumably not 

 attaining inflation of Eboraciceras by some 10 per cent. Marked 

 prorsiradiation. Well-developed arcuation of ribs on narrowish rounded 

 venter. Whorls convergent. Suture line with rather short broad lobes, 

 L 1 about as long as EL, L 2 fairly developed. 



Chamoussjtia, which is much earlier in date, has remains of similar 

 prorsiradiation. Apart from date it could not be involute development, 

 for present genus gives no signs of attaining the much swollen galeatiform 

 whorl with distinct carination. 



Genus, VERTUMNICERAS, nov. 

 Type, Am. vertumnus, Leckenby, Holotype, Y.T.A. CXVI a 

 A Cadoceratid series distinguished by coarse subflexicostse which are 

 ong cm venter, where they form a herring-bone pattern rising to a 

 slight discontinuous ridge. (Suture-line with long L l and quite short L^, 

 atnitum, PL CXVI c). 



