3 o TYPE AMMONITES— III \ov. 



1920 



Pseudobigotella, but condemns Pseudobigotella, as, in his opinion, an 

 unnecessary addition to nomenclature. 



Polygyral ; thin ; rather small ribs which cross periphery with a 

 V-curve ; s.l. quite simple — EL longer than Li — very little obliquity to 

 inner part. Cf. PI. CXCI. 



Pseudobigotella has the Perisphinctean venter, presumably having 

 passed through the stages of Parkinsonian and Bigotitean venters ; 

 but this is not yet proved : it may be inferred from evidence of other 

 genera. 



HASELBUBGITES, gen. nov. Like Bigotellapetri, Nicolesco, iv, 5. 

 Distinct from Bigotites in suture-line — ES is shorter instead of longer 

 than Li, and it lacks a lateral branch ; guide-line cuts above aux. 2, 

 and there are 4 aux. in a long hanging part which extends well below 

 guide-line. Genoholotype, H. admirandus nov. Like B. pelri, but 

 more massive, ornament heavier, umbilicus smaller, lateral ribs obsoksce 

 about 170 mm. diam. From Haselbury, Somerset (purchased) ; Inf. 

 Oolite [Parkinsoni z.] ; S. B. Coll. 654 ; S. 129, 33, 36, 42 ; 218, 36, 29, 

 37 ; max. c. 410 + . Its date is presumably c. truellei ; but Strigoceras 

 truellei appears to be lacking from Haselbury. A Morphoceratid of 

 defrancii pattern occurs in the same bed — a light yellow stone, finely 

 oolitic, soft. (' Top bed ' [1] or ' Brash ' [2], Hudleston, Mon. Gast., 

 Pal. Soc, 1887, p. 31). 



Family ZIGZAGICERATIDM, nov. 



Descendants of those coronates which have zigzag ornament — later 

 coronates than the ancestors of the Parkinsonidse. These lose their 

 parabolic curves as soon as they enter the costate stage, and they show 

 no stage of intermittent parabolic curves like the Perisphinctidee. Also 

 constrictions are not developed. 



The s.l. in the zigzag stage is comparatively simple, of Stepheoceratid 

 style ; in the costate stage, or even earlier in the stout forms, it rapidly 

 develops to become very elaborate, distinguished by large EL, with 

 large accessory branch, and by large aux. 2 spreading across the whorl. 

 These characters, though there may be decay of s.l., should yet remain 

 relatively distinguishing. 



Genera, Procerites, Zigzagiceras. 



Procerites, Siemiradzki 1898 (Op. cit. p. 78.) " V. Abtheilung. 

 Subgen. Procerites nob. C. Mutationsreihe des P. procerus Seeb." (pp. 

 78, 79). The earliest whorls show lateral ornament like that of Stephano- 

 ceras zigzag — on a smooth under-surface zigzag-like coarse distant ribs 

 which on the dorsal [ventral] margin swell up into spine-like little 

 knobs (Siemir. p. 78). 



From the character of its inner whorls Procerites is undoubtedly 

 a descendant of the Stephanocerata in a narrow sense (Siemir., p. 79). 

 The development from " Stephanoceras ' zigzag had been illustrated by 

 S.Buckman, Q.J.G.S., XLVIII, 1892, 447, and the likeness of inner whorls 

 of zigzag forms to coronates (Am. blagdeni — Teloceras) was also pointed 

 out. 



Unfortunately, the identification of Am. procerus seems to be 

 incorrect, now that s.l. of zigzag costates has been worked out. 

 M. A. de Grossouvre also points this out (Bull. Soc. geol. Fr. (4) XVIII, 

 (1919), 387). Am. procerus, Siemiradzki's interpretation, is geno- 

 lectotype of Procerites (Y.T.A. II, 1914, ix). 



