ORDER II 



A.MMONOIDEA 



(Amm.) Bates*, (JaMi sp. (I'nln.fniit. ('ulifurni", II., 1'U i'n, :M ; n<>n .1. //'-. I.. 1'i. 

 13); PleuropachyJ.isnui, ^cn. nov. Type P. (Amm.) Hoffman i, (!abl> .-]. ( 'r-t i 



Fio. 1186. 



A , Baculites anceps, Lam. B, B. 1 

 Lam. Upper Cretaceous ; Maestricht. 



Fio. 1184. 



Macroscaphites Ivanii, d'Orb. sp. 

 Upper Neocomian ; Mallenewitz, 

 Carpathia. 



Fio. 1185. 



Ptychoceras Puzo- 

 sianum, d'Orb. sp. 

 Barremian ; Vergons, 

 Basses Al]i"s. 



Fio. 1187. 



Suture-line of Dipli>mtx-er<'.- 

 Defr. Uppermost Cretaceous ; Tiv>villi-, 

 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 hav- constrictions and large 

 costae at intervals, but no tubercles at any slayv. 



Macroscaphites, Meek (Fig. 1184); Leptoceras, Costidiscus, 

 Uhlig; Tropaeii-in, S>\vb. ; Ptychoceras, d'Orb. (Fig. 1185); 

 Diptychoceras, Gabb ;* Cyrtochilus, Meek (Scipionoceras, Hyatt) ; 

 Baculites, Lam. (Fig. 1186); Diplomoceras, gen. nov. (Fig. 

 1187). Type D. (Ham.) cylindraceum, d'Orb. sp. ; Anahamu- 

 lina, gen. nov. (Fig. 1188, A). Type A. (Ham.) subcylindrica, 

 d'Orb. sp. Cretaceous. 



Family 8. Scaphitidae. Meek. Two or more rows of 

 tubercles developed in tin- i-pli.-bi.- <>r ,vrnntic stage; costae 

 continuous across tlic vnitrr ; ajH-rturc evenly constricted on 

 the sides and with a slight, brrtad 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 ephebic stages of Scaphites possess the 

 costae, form, and general aspect of Pachydiscus, and there are 

 species transitional between them. 



Fi... 1188. 

 A, Aiiiilmtii 



i/c/V", d'Orb. sp. B, Sutuiv- 

 line of A. I^rioli, Uhlig sp. 

 Neocomian ; Angles/Bassea 

 Alpes (after Uhlig). 



