ORDER II AMMONOIDEA 559 
involute, but stout-whorled and keelless, becoming more compressed, and having a broad 
slightly elevated median ventral ridge in more specialised genera. Sides have at least 
one line of nodes in primitive forms, and are more or less completely costated with 
several lines of tubercles in specialised shells. Sutures in the young and in primitive 
genera have a magnosellarian aspect, but when the broad 
internal saddles become divided, the internal inflections 
resemble those of Lecanitidae. In primitive forms 
(Olentkites) the saddles are broad and very shallow ; lobes 
entire, and ventral lobe divided by a larviform siphonal 
saddle, which is sometimes entire. 
The large nodes and stout volutions of primitive forms 
indicate parallelism with Stephanites and Parastephanites 
of-the preceding family. Saddles and lobes have the 
typical ceratitic outlines, as a rule, but in some forms 
the auxiliary line may be extended as in Gyronitidae. 
Occasionally, also, costae may cross the venter as in 
Sibiritidae. 
Ceratites, Haan (Fig. 1143); Danubites, Mojs.; Bala- 
tonites, Mojs.; Rezflingites, Arthaber; Gymmnotoceras, Hyatt; Fic. 1144. 
Paraceratites, gen. nov. Type P. (Cer.) elegans, Mojs. sp. Paraceratites trinodosus, Hauer sp. 
(Fig. 1144); Olenikites, gen. nov. Type O. (Din.) spini- Cre ieinntiicn, Bona Huneary 
plicatus, Mojs. sp. Keyserlingites, gen. nov. Type K. 
(Cer.) subrobustus, Mojs. sp.; Arctoceras, gen. nov. Type A. (Cer.) polaris, Mojs. sp. 

TV. Trroniripa. 
Primitive forms compressed, discoidal, and have only one pair of narrow entire lateral 
lobes, and two broad entire saddles with cncomplete lobes in the umbilicus as im Puarodo- 
ceras. Number of inflections seldom exceeding three or four, 
and the auxiliary sutures never much extended. 
Family 12. Tirolitidae. Mojsisovics (pars). Com- 
pressed, discoidal, or involute shells resembling Dinaritidae 
in their sutures, and having entire saddles and slightly 
denticulated lobes. Ventral lobe may remain entire until 
a late stage in some forms, but as a rule it is divided, and 
siphonal saddle is small and often entire. Shells have a 
line of nodes on the ventro-lateral angles, and the venter 
is invariably smooth and convex. 
Includes Tirolites (Fig. 1145) and Metatirolites, Mojs., 
from the Alpine Trias.  Sub- Family C1LyponIrrNae. 
Sutures similar to 7’rolites, but costae interrupted on the 
venter, which is often channeled. Includes Clydonites, 
Eremites, Hauer; and Ectolcites, Mojs. ‘Trias. 
Family 13. Dinaritidae. Mojsisovics (pars). 
Sutures resembling Tvrolites in having only two broad 
Fic. 1145. saddles, one pair of first lateral lobes, and incomplete lobes 
Tirolites Cassianus, Quenst. sp. at the umbilicus. Shells smooth, or with coarse folds most 
ES cede eee nea® prominent at the umbilical shoulders; sides more or less 
flattened or plano-convex, and venter rounded. 
Dinarites, Mojs. (2?) Pseudoharpoceras, Waagen ; Pseudodinarites, gen. noy. Type 
P. (Din.) mahommedanus, Mojs. sp. Trias. 
Family 14. Buchitidae. Primitive forms similar to Celtitidae, with smooth 
elevated venter; more specialised shells with slight keel on the narrow venter, and 
simple costae or folds on the sides. Sutures have entire outlines, or lobes but slightly 

