CLAS8 V 



CEPHALOPODA 



663 



iiiore nearly equal. Doi-sal sutures generally have three pairs of zygoiis saddles and 



two pairs of lobes in tlie coronate discoidal 



forms. 



Stefhanoceras Neiim. (Fig. 1285); Gado- 

 mites Mim.-Chalnis. ; S2)haeroceras Bayle (Fig. 

 1281); Emiida Buckman ; Normannites 

 Miin.-Clialmas (Fig. 1282); Macrocephalites 

 Sutner (Fig. 1283); Sutnerm Zittel (Fig. 1284). 

 Inferior Oolite. 



Sutneria platynota (Rein.). Upper 

 Jura (Tenuilobatus Beds) ; Balingen, 

 Wärtern barg. 



Fig. 1l>85. 



StepTiiiTUKeras cor(ynati(s (Brug.). Callovian 



Dept. Nievre, France. 1/3- 



Subfamily C. Cadoceratinae Hyatt. 



More specialised, comjDressed, and involute forms tend to evolve shells with 

 crenulated keels, and sometimes Channels also. Costae of Gadoceras divided as in 

 Steplianoceratinae, 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 the adult of Quenstedtoceras. 



Tills group is remarkable for the close parallelism of some of its genera with Amaltheidae, 

 but the young are very distinct. Development and adul t stages of Gadoceras with its discoidal 

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

 and sutures also show relationsliip with Steplianoceratinae. 



Gadoceras Fischer ; Quenstedtoceras Hyatt ; Gardioceras Neumayr and Uhlig ; 

 Neumayria Nikitin. Kelloway. 



Subfamily D. Perisphinctinae Steinmann.^ 



An extensive series of discoidal genera having rounded or subquadrangular 

 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 the ventro-lateral angles. Inner parts of sutures steeply 

 inclined apicad, and dorsal sutures have a long pair of first dorsal saddles, usually two 

 additional pairs of saddles, and two pairs of lobes. All of these are so decidedly 

 inclined apicad that they often appear as a single pair of complex saddles. 



These genera are morphic equivalents of the Liassic Dactylioidinae and are derived from 

 the same common stock. Young have depressed trapezoidal volutions and often minute 

 tubercles on ventro-lateral angles, but are otherwise smooth, like the young of Gadoceras 

 sublaeve. They become compressed in the neanic stage and rapidly assiime the discoidal 

 Perisphinctean form and costae without tubercles. 



Perisphinctes Waagen {Grossüuvria, ProceriteSy Ghoffatia Siemirad.) (Figs. 1286- 



^ Sieviiradzki, ./., Monographische Beschreibung der Gattung Perisphinctes. Palaeontogr. 1898, 

 vol. xlv. See also R. DouvilU's recent studies of Gardioceras, etc., 1913. 



