72 DH. I/. P. SPATH ON THE AMMONITES [vol. lxxix, 



(C) Genus Agassiceras Hyatt. 



This is here taken to include the striaries-sauzianus group, as 

 emended by S. Buckman, 1909 (non Agassiceras, Hyatt emend. 

 Haug 1887). It is represented by a number of forms that range 

 from below Table Ledge (53) : that is, from below the limits of 

 the present section, to the alcinoe bed (70). Agassiceras striaries 

 (Quenstedt), A. sauzeanum (A. d'Orbignj^), A. spinaries (Quen- 

 stedt), distinguished from the nearly allied French species by closer 

 costation, are the commonest forms, the smooth A. striaries 

 apparently characterizing the lower half of these beds. A new 

 species, A. reynesi, nom. no v. ( = Ammonites multicostatus 

 Sowerby, var. spinaries Quenstedt in Reynes, ' Monographie des 

 Ammonites ' 1879, pi. xxiv, figs. 25-28, Coll. W. D. L. 4236), 

 forms a morphological transition to some species of the genus 

 Pararnioceras, dealt with below, and Herbich's Arietites stellaris 

 =A. obtusus var. vulgaris Vadasz 1 seems also to belong to this 

 group. Agassiceras cf. terquemi (Reynes), 2 recorded from bed 

 70c, is a doubtful example; accordingly, no Agassiceras of the 

 typical sauzeanum type has been found in bed 70 c. 



With regard to the interpretation of the genus Agassiceras, it 

 may here be remarked that forms comparable to Ammonites per- 

 sonatus and A. resupinatus Simpson, probably also A. subtaurus 

 Reynes and JEtomoceras decipiens nov. ( = A. multicostatus 

 Simpson non Sowerby, B.M. C 22067 a, b=' Agassiceras sp.,' 

 pi. clxxxvii, fig. 3 in Buckman, op. cit. vol. iii. 1920) occur in the 

 scipionianum beds of Skye and Yorkshire, and are here excluded 

 from Agassiceras ; but the ancestral forms of both AEtottwceras 

 and Agassiceras have to be looked for in the stock that produced 

 the still earlier ' Coronicerates ' discussed in my paper on the 

 Lower Lias of Skye. The tendency of Agassiceras, however, is to 

 * delay ' the development of bisulcation, common to all these deri- 

 vatives of the genus Ammonites sensu stricto {Ammonites 

 Bruguiere, restricted to the group of A. bisulcatus (Bruguiere) 

 A. d'Orbigny, pi. xliii 3 ). A similar tendency in early ' Eparnio- 

 ceras ' leads to Cymbites, which genus, therefore, cannot be united 

 with Agassiceras, as was done by Haug 4 and Pompeckj. 5 Like 

 Psilopliyllites Spath, 6 Cymbites is a good illustration of simpli- 

 fication. The resemblance of species of Agassiceras of the type of 

 A. davidsoni (Dumortier non A. d'Orbigny) or of A. berardi 

 (Dumortier) 7 with the scaphitoid Cymbites is, moreover, not very 

 ■close. 



1 ' Unterliasische Fauna von Als6rakos, &c.' Mitt. Jahrb. K. Ung. Geol. 

 Anst. vol. xvi (1908) p. 377 (71) & pi x, fig. 3 only. 



2 'Monographie des Ammonites' 1879, p. 4 & pi. xix, figs. 9-12. 



3 L. F. Spath, Geol. Mag. 1922, p. 173. 



4 Neues Jahrb. vol. ii (1887) p. 93. 



° ' Ueber Ammonoiden mit " anormaler Wohnkammer " ' Jahresh. Ver. 

 Yaterl. Naturk. Wurtt. vol. 1 (1894) p. 238. 



6 'Development of Tragophylloceras loscombi' Q. J. G. S. vol. lxx (1914) 

 p. 351. 



7 ' Etudes Paleontologiques sur les Depots Jurassiques du Bassin du 

 Ehone ' vol. ii (1867) pi. xxi, figs. 5-7. 



