ORDER II AMMONOIDEA 
571 
(Amm.) Batesi, Gabb sp. (Palaeont. California, IL, Pls. 20, 21; non A. Batesi, L., Pl. 
13); Plewropachydiscus, gen. nov. 

4 
Zi 
oo, 
= 
Lam. 


Fic. 1185. 
Fic. 1184. 
Ptychoceras Puzo- 
Macroscaphites Ivanii, a’Orb. sp. sianum, @ Orb. sp. 
Upper Neocomian; Mallenewitz, Barremian ; Vergons, Defr. 
Carpathia. Basses Alpes. Manche. 
Family 7. Macroscaphitidae. Symmetrical, closely 
coiled, discoidal ammoniticones during young stages (and _per- 
sistently so in primitive forms), but becoming uncoiled in 
gerontic stages or earlier in the ontogeny of phylogerontic forms, 
and finally straight in some genera. Antisiphonal lobe short, 
and in some genera trifid. Shells have constrictions and large 
costae at intervals, but no tubercles at any stage. 
Macroscaphites, Meek (Fig. 1184); Leptoceras, Costidiscus, 
Uhlig; Tropaeum, Sowb.; Ptychoceras, VOrb. (Fig. 1185) ; 
~ Diptychoceras, Gab ; Cyrtochilus, Meek (Scipionoceras, Hyatt) ; 
Baculites, Lam. (Fig. 1186); Diplomoceras, gen. nov. (Fig. 
1187). Type D. (Ham.) cylindracewm, VOrb. sp.; Anahamu- 
lina, gen. nov. (Fig. 1188, A). Type A. (Ham.) subeylindrica, 
VOrb. sp. Cretaceous. 
Family 8. Scaphitidae. Meek. 
tubercles developed in the ephebic or gerontic stage; costae 
continuous across the venter; aperture evenly constricted on 
the sides and with a slight, broad rostrum on the venter, 
caused by recession of the lateral curves. There is a dorsal 
lappet, but this is long and bent only in Jahnnites. The 
young and sometimes ephebice stages of Scaphites possess the 
costae, form, and general aspect of Pachydiscus, and there are 
species transitional between them. 
Type P. (Amm.) Hoffmant, Gabb sp. 

Two or more rows of 
Cretaceous. 



Fic. 1186. 
A, Baculites anceps, Lam. B, B. Foujasi, 
Upper Cretaceous ; Maestricht. 

Fic. 1187. 
Suture-line of Diplomocerascylindraceum, 
Uppermost Cretaceous ; Tresyille, 

Fic. 1188. 
A, Anahamulina subeylin- 
drica, d’Orb. sp. B, Suture- 
line of 4. Lovrioli, Uhlig sp. 
Neocomian ; Angles,’ Basses 
Alpes (after Uhlig). 
