586 



MOLLUSCA 



SUB-KINGDOM VI 



and Camp. ; Lyticoceras, gen. nov. (Fig. 1225). Type L. (Amm.~) cryptoceras, d'Orb. sp. ; 

 (?) Vascoceras, Choff. 1 Cretaceous. * 



Family 26. Hamitidae. A provisional group of uncoiled shells having single 

 ostae crossing the venter uninterruptedly > and no tubercles at any stage. 



Hamites, Park. ; Hemibaculites, gen. nov. Type H. (Toxoc.) obliquatum, d'Orb. sp. ; 

 Dirrymoceras, gen. nov. Type D. (Ancyl.) simplex, d'Orb. sp. ; Torneutoceras, gen. nov. 



Fi.;. 1225. 



Lyticoceras Noricum, Sowb. sp. ( = Hoplites anMygonius, Neuni.). 

 Neocomian ; Achim, near Borsum, Prussia. 



Fi.:. 1226. 



Torneutoceran 



Sowb. sp. Gault; Folke 

 stone. 



(Fig. 1226). Type T. (Ham.} attenuatus, d'Orb. sp. Possibly here also should be 

 placed Helicoceras and Heteroceras, d'Orb. ; and Lindigia, Karstens all asymmetrical 

 spirals, but in old age forming a secondary crook striking off from the spire. 

 Cretaceous. 



X. COSMOCERATIDA. 



Highly taberculated and costated forms having a smooth zone on the venter or costae 

 extending across it, but never with a line of median ventran tubercles nor a keel at any 

 stage. Numerous phyloyerontic uncoiled forms occur in the Cretaceous. 



Family 27. Cosmoceratidae. Discoidal and involute forms having at a 

 comparatively early stage or throughout life two or three rows of large tubercles 

 on each side, and costae interrupted on the venter by a smooth median zone or 

 channel. 



Late stages of all genera except Cosmoccras and Phricodoceras have costae continuous 

 across the flattened venter, and species of the latter indicate possible transitions to 

 Amblycoceras. All forms have a Cosmoceran stage quite distinct from the young of 

 Morphoceratidae. 



1 P. (jho/at. Receuil d'etucles paleontologiques sur la fanne cretacique du Portugal, Les 

 Ammom'es du Bellasien, etc. Lisbonne, 1898. 



