580 MOLLUSCA SUB-KINGDOM VI 
Stepheoceras, Buckman (Stephanoceras, Neum.; Cudomites, Mun.-Chalm.) ; Sphaero- 
ceras, Bayle (Fig. 1207); Emileia, Buckman ; 
Normannites, Mun.-Chalm. (Fig. 1208); Macro- 
cephalites, Sutner (Fig. 1209); Sutneria, Zittel 
(Fig. 1210); Erymnoceras, gen. noy. (Fig. 1211). 
Type E. (Amim.) 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 
Fic. 1208. also. Costae of Cadoceras divided as in Stepheo- 
or EMEE Bore na oe In- ceratidae, but other genera usually develop two 
, lines of tubercles. Young of Newmayria more or 
less costated, but sides and keel become smooth, and in some species resemble adult of 
(uenstedtoceras. 

This family is remarkable for the close parallelism of some of its genera with Aimaltheidae, 
but the young are very distinct. Development and adult stages of Cadoceras with its discoidal 

Fic. 1209. 
Macrocephalites macrocephalus, Schloth. sp. Upper Dogger (Callovian), Ehningen, Wirtemberg. 
and much depressed volutions plainly show derivation from Coeloceran stock, while its form 
and sutures also show relationship with Stepheoceratidae. 
Cadoceras, Fischer ; Quenstedtoceras, Hyatt ; Cardio- 
ceras, Neum, and Uhlig; Newmayria, Nikitin ; Amoebo- 
ceras, gen. nov. Type A. (Amm.) alternans, von Buch 
sp. Kelloway. 
Family 16. Perisphinctidae.! An extensive 
series of discoidal genera having rounded or subquad- 
rangular volutions, and costae single on the sides, but Fic. 1210. 
split into two, three or more on the venter, which they Sutneria platynotus, Rein, sp. Upper 
cross uninterruptedly. Splitting does not begin as a Witeebeete Beds); Balingen, 
rule at umbilical shoulders, but near ventro - lateral 
1 Siemiradzki, J., Monographische Beschreibung der Gattung Perisphinctes (Palaeontogr. Bd. 
XLV.), 1898. 

