648 MOLLUSCA thylüm vi 



entire. Shells have a line of nodes on the ventro-lateral angles, and the venter is 



invariably smooth and convex. 



Includes Tirolües (Fig. 1235) and MetatiroUtes Mojs., froni tlie Alpine Trias and 

 froiii Idaho. The siibfamily of Clydonitinae has siitnres 

 similar to Tirolües, biit costae interriipted on the venter, 

 which is often channelled. Includes Gkjdonites and Eremites 

 Hauer ; and Ectolcites Mojs. Trias. 



Subfamily C. Dinaritinae Mojsisovics ^pars). 



Sutures resembling Tirolües in having only two broad 

 saddles, one pair of first lateral lobes, and inconiplete lobes 

 at the umbilicus. Shells smooth, or with coarse folds 

 most prominent at the umbilical Shoulders ; sides more or 

 less flattened or planoconvex, and venter rounded. 



Dinarites Mojs. ; Cuccoceras Diener. Trias. 



Subfamily D. Buchitinae Hyatt. 



Primitive forms similar to Celtitinae, with smooth 

 elevated venter ; more specialised shells with slight keel on 

 Tirolües cassianus (Quenst.) the narrow venter, and simple costae or folds on the sides. 

 Lower Trias ; Grones-Hof, near Sutures have entire outlines, or lobes but slightly denti- 



st Cassian Tvrol. o ./ 



culated ; and when the saddles are completely divided 

 their marginals are small. Sutures otherwise similar to those of Dinaritinae, and the 

 young have a Dinarites stage. Antisiphonal lobe entire and bifid in some forms. 

 Buchües, Helictites, Phormedites, Parathishites and Glyphidites Mojs. Trias. 



Fig. 1235. 



Subfamily E. Arpaditinae Hyatt. 



Differs from the Buchitinae in the tendency to form channelled venters bordered 

 by two ridges, which may be either tuberculose or smooth. 



Ärpadües (Fig. 1236), Klipsteinia, Dütmarites, Muensterües, Steinmannües, Dafli- 

 nües, Dionites, Brepanües, Heraclües, Guemhelües, 

 Cyrtopleurües and Acanthinites Mojs. Trias. 



Subfamily F. Trachyceratinae Hyatt. 



Discoidal and involute shells with well-defined and 

 often profusely tuberculated costations which are 

 interrupted on the ventral aspect by a smooth zone 

 or Channel. This may in some specialised forms 

 becorae a d istin et Channel bordered by tuberculated 

 ridges. Lobes and saddles completely divided by 

 marginals, but these do not become very long nor 

 complex. 



Distichites, Trachyceras (Fig. 1237), Protrachyceras (Fig. 1238), AnolcÜes, Sand- 

 hngites, Siremtes, Anasirenites, DiplosirenÜes and Glionües Mois. (Figs 1239, 1240). 

 Trias. (?) Hesperites Pompeckj. Rhaetic. 



Subfamily G. Choristoceratinae Hyatt. 

 Discoidal ammoniticones in primitive forms, becoming uncoiled phylogerons, and 

 finally even complete baculiticones in the most specialised species. Sutures also 



Arpadites cinensis Mojs. Keuper 

 Esino, Lombardy. 



