566 



MOLLUSC A 



SUB-KINGDOM VI 



solid broad bifid saddles. The division of these by large secondary lobes is similar to 

 that which occurs in the first laterals of Manticoceras and Sporadoceras, but affects more 

 of the primitive laterals. Aperture with only short broad crests on the venter. 



Includes only Didy mites, Mojs. (Fig. 1166), from the Alpine Trias. 



Family 8. Cladiscitidae. Zittel. Some shells resembling Arcestidae, but 

 typically the sides are flat, venter plano-convex, and surface usually covered with 

 longitudinal ridges. Sutures similar to Arcestidae, but more complex, the saddles 

 being reduced in many forms to thread-like narrowness. Growth-lines like those of 

 Didy mites on the sides, but have crests at the ventro-lateral angles, and very broad 

 ventral crests. 



Cladiscites (Hypocladiscites), (Fig. 1167); Psilocladiscites, Procladiscites, Paracladis- 

 cites, Mojs. Trias. 



IV. PHYLLOCERATIDA. 



Shells as a rule vrith peculiar, prominent bands of growth. Saddles in primi- 

 tive genera have the monophyllic bases of those in Popanoceratidae, but in more 

 specialised groups the marginal saddles alone retain the same rounded outlines. Dorsal 

 saddles and lobes are, as a rule, at least three in number. Antisiphonal lobe often 

 bifid, and retains either entire outlines on both sides, or with a few simple marginals^ 

 or has but one pair of short lateral branches. Aperture with well-marked but short 

 ventral crest. 



Family 9. Megaphyllitidae. Mojsisovics. Conchs compressed, discoidal, or 

 involute. Sutures with primitive monophyllic saddles, and more regular in the 



relative size of the lobes 

 and saddles and in their 

 marginals than succeed- 

 ing families. Anti- 

 siphonal lobe bifid but 

 otherwise entire. 



Monophyllites (Fig. 

 1168), Megaphyllites, 

 Mojs. (Fig. 1169); 

 Mojsvarites, Pompeckj ; 

 Discophyllites, gen. nov. 

 Type D. (Lytoc.} patens, 

 Mojs. sp. Trias. 



Family 10. TJs- 

 suritidae. Conchs 

 compressed, discoidal, 

 and involute. Sutures 



Fie. 1168. 



MonophylUti'x >'/,///;, Ilauor sp. 

 Trias ; Rothelstein, near Aussee, Austria. 



mono- 

 ling, near Aussee, Austria, phyllic first lateral 

 MiStT 11 " 6 f M ' JarbaS> saddles, the second 

 laterals more or l-s> 

 pointed in Ussuria. Auxiliary series remarkably irregular, and all the lateral lobes 

 with very large, more or less pointed, but still phylloidal marginal lobes and saddles. 

 Ventral lobe broad and short, and siphon al saddle very large. 



Ussuria, Diener ; Ussurites, gen. nov. Type U. (Monophyl) sichoticus, Diener sp. 

 Trias. 



Family 11. Phylloceratidae. Zittel. Principally involute shells with very 

 complex sutures, which, however, still retain monophyllic outlines in the marginal 

 saddles. Antisiphonal lobe with entire sides, or with only one pair of short lateral 

 branches, and extremities usually bifid. 



