Hyatt.] 338 [April 4, 



or marked by furrows. The lobes and saddles are numerous and 

 club-shaped. The ventral lobes are divided by prominent narrow, 

 siphonal saddles, carrying small funnel lobes. Three or more 

 pairs of lobes are divided by marginal saddles, either single or 

 double, the terminations of the lobes being either bifid or trifid. 



Popan. (Gon.) Kingianum, M., V., K., Russia and Ural, pi. 27, 

 fig. 5, Koninckianum, ibid, pi. 26, fig. 4, Soboleskyanum, ibid, 

 pi. 26, fig. 5. The extreme form is the Popan. (Arcestes) antiquum, 

 sp. Waagen, Foss. of Salt. Range, Pal. Ind. ser. 13, 1, pi. 1, fig. 

 10, and this is a close ally of Waagen's Cyclolobus Oldhami. 1 



[Remarks.] 



Xenodiscus Waagen, is discoidal and similar to Ophiceras, 

 Griesbach, Rec. Geol. Surv. India, Vol. 13, pt. 2, pi. 3, and this 

 is transitional to -Otoceras, ibid, pi. 2, which is highly involute. 

 These Dyassic forms are the immediate radicals of the Triassic 

 Ceratitinae. The annular lobes are divided by minute saddles, 

 and the sutures are distinctly ceratitic and cannot be closely com- 

 pared with any of the Goniatitinae. The Ceratitinae also in our 

 opinion include, Hungarites, Ceratites, Dinarites, Tirolites, Arpad- 

 ites, Beneckia, Meekoceras, Kipsteinia, Balatonites, Trachyceras, 

 Celtites, Badiotites, Proceltites, Lecanites, Carnites, Tropites, 

 Acrochordiceras, Helictites, and Choristoceras. The larvae of 

 these, and many adults, show sutures similar to those of Nannites, 

 Mojsis. pi. 39, and to the Dimerocerae among Goniatitinae. If 

 this view is admitted, the Magnosellaridae and Glyphioceratidae 

 will become the distal Paleozoic radicals of the Ceratitinae of the 

 Dyas and Trias, and the Ammonitinae be confined to Psiloceras 

 and Aegoceras, and their descendants in the Jura. These two 

 genera must be regarded as offshoots of the Prolecanitidae, with 

 either Gymnites or Monophyllites as the immediate radicals. 



1 Cyclolobus, Waagen, Pal. Ind. ser. 13, 1, p. 21, has for the type Cycl. Oldhami 

 ibid., pi. 1, fig. 9. This genus is very important since it enables us to show the grada- 

 tions by which the Prolecanitidae approximate to Arcestes, Ptychites, and Monophyll- 

 ites. Cyclolobus is a true Ammonite and cannot be separated from the Triassic groups 

 we have mentioned either by its form or sutures; and the phylliform marginal saddles, 

 which are so persistent in the succeeding forms begin to make their appearance in 

 this species. They en-'ble us to co.mect Cyclolobus with Monophyllites, and the 

 last with the groups of Lytoceras and Phylloceras. Mojsisovics regards the phylli- 

 form saddles as having no genetic significance. We think the facts are against him 

 in this opinion, and that, on the contrary, there are strong evidences of the direct 

 descent of the Phylloceratidae from the Prolecanitidae. • 



