580 



MOLLUSCA 



SUB-KINGDOM VI 



Stepheoceras, Buckman (Stephanoceras, Neuin. ; Cadomites, Mun.-Chaha.) ; Hphaero- 



ceras, Bayle (Fig. 1207) ; Emileia, Buckman ; 

 Normannites, Mun.-Chalm. (Fig. 1208); Macro- 

 cephalites, Sutner (Fig. 1209); Sutneria, Zittel 

 (Fig. 1210); Erymnoceras, gen. nov. (Fig. 1211). 

 Type E. (Amm.) coronatum, Brug. sp. Inferior 

 Oolite. 



Family 15. Cadoceratidae. More special- 

 ised, compressed, and involute forms tend to evolve 

 shells with crenulated keels, and sometimes channels 

 also. Costae of Cadoceras divided as in Stepheo- 

 In ' ceratidae, but other genera usually develop two 

 lines of tubercles. Young of Neumayria more or 



less costated, but sides and keel become smooth, and in some species resemble adult of 



Quenstedtoceras. 



This family is remarkable for the close parallelism of some of its genera with Amaltkeidac, 

 but the young are very distinct. Development and adult stages of Cadoceras with its discoidal 



FIG. 1208. 



Normannites Braikvnridgei, Sowb. sp. 

 i'erior Oolite ; Baynx, Calvados. 1/1- 



FIG. 1209. 

 Macrocephalites macrocephalus, Schloth. sp. Upper Dogger (Callovi 



i), Elmingen, Wiirtemberg. 



and much depressed volutions plainly show derivation from Coeloceran stock, while its form 

 and sutures also show relationship with Stepheoceratidae. 



Cadoceras, Fischer ; Quenstedtoceras, Hyatt ; Gardio- 

 ceras, Neum. and Uhlig ; Neumayria, Nikitin ; Amoebo- 

 ceras, gen. nov. Type A. (Amm.} alternans, von Buch 

 sp. Kelloway. 



Family 16. Perisphinctidae. 1 An extensive 

 series of discoidal genera having rounded or subquad- 

 rangular volutions, and costae single on the sides, but 

 split into two, three or more on the venter, which they 

 cross uninterruptedly. Splitting does not begin as a 

 rule at umbilical shoulders, but near ventro - lateral 



1 Siemiradzki, /.. Monographische Beschreibung der Gattimg Perisphinctes (Palaeontogr. Bd 

 XLV.), 1898. 



FIG. 1210. 



Sutneriaplatynotui, Rein. sp. Upper 

 ira (Tenu/l<i!itii* l'''ls); Balingen, 



