ORDER II AMMONOIDEA 561 
auxiliaries. Ventral lobe in some forms similar to that in 7%rolitidae, and mode of 
generation of adventitious inflections in Placites is 
the same as In Tvbetitidae; that in Pinacoceras is 
unknown. 
Placites, Bambaganites, Pinacoceras (Figs. 1149, 
1150), Mojs. Trias. 
Family 19. Choristoceratidae. Discoidal 
ammoniticones in primitive forms, becoming un- 
coiled phylogerons, and finally even complete 
baculiticones in the most specialised species. 
Sutures also phylogerontic, having only six entire 
or very faintly denticulated lobes, and six entire 
saddles. Ventral lobe divided, and the anti- 
siphonal either entire or bifid at its extremity. 
Dorsal lobes and saddles otherwise entire. Con- 
nected through Polycyclus with Buchites, according 
to Mojsisovics. 
Polycyclus (Fig. 1151), Periplewrites, Mojs. ; 
Choristoceras (Fig. 1152), Rhabdoceras (Fig. 1153), nee , 
Hauer. Trias. ait ria; Rothelsteln, Bsa see ea rea 
; : 
Family 20. Cochloceratidae. Turriliti- 
cones with costae similar to those of preceding family, but more or less asymmetrical 
ott oP Be | 
Fic. 1150. 
Pinacoceras Metternichi, Hauer sp. Keuper; Someraukogel, near Hallstadt, Austria. Suture-line reduced 
(after Hauer). 

AdL EL 

e 
in consequence of the asymmetry of the spires. Lobes reduced to four in number, 
J y i 
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Fig. 1153. 
Wigs 1151. Fig. 1152. Rhabdoceras Suessi, Big. 1154 
Polycyclus nastur- Choristoceras  Marshi, Hauer. Keuper ; Cochloceras Fischeri, 
tiwm, Dittmar sp. Hauer, Rhaetic; Kendel- Sandling, near Hauer. Sandling, 
Keuper ; Sandling, engraben ain Osterhorn, Aussee (after near <Aussee (after 
near Aussee. near Salzburg. Hauer). Hauer). 
and there are other phylogerontic suppressions. Funnels monochoanitic, collars 
absent. 
Cochloceras, Hauer (Fig. 1154); Paracochloceras, Mojs. Trias. 
WOT 
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