237 Midway Stage 123 



"Genus Enclimatoceras Hyatt. 



" Bnclimatoceras includes species of the Trias to the Tertiary, 

 inclusive, which are connected by the outlines of their sutures. 

 The whorls are involute from an early stage, and compressed. 

 The abdomens are rounded, but become acute in many species. 

 The sutures have prominent ventral saddles, flatted in species 

 with rounded abdomens, and acute in those with acute abdomens; 

 never divided by ventral lobes. The lateral lobes are deep, and 

 the lateral saddles well marked. The ventral saddles in the 

 young are broad and closely resemble the ventrals of the Herco- 

 glosscB, as do also the broad lateral saddles of the later larval 

 stages in some species. There are no annular lobes at any stage 

 in the Triassic, according to Mojsisovics. They do not seem to 

 be present in some of the Jurassic and Cretaceous species, at 

 least during the early stages, and are very small in some adults. 

 The Triassic species are nearly related to Grupoceras, according 

 to Mojsisovics' figures and descriptions in ' Das Gebirge um 

 Hallstatt. ' The siphon in this type is a little below the center 

 in the young, though ventral in the adult; and this also agrees 

 with the characteristics of Bnclimatoceras styriacus, sp. Mojsisovics, 

 of the Trias, and Grupoceras. Nevertheless there is no ventral 

 lobe at any stage; the annular lobe is absent in the Triassic 

 forms, and young of later forms; and the siphon in two species 

 is short- funneled, with connective walls, or ellipochoanoidal. 

 Type, Enclivi. {Naut.) ulrichi White." 



^ ' Enclimatoceras (^Nautihis) ulrichi White. 



>}; ^ >i< ;i< >i< :^ 



"Shell moderately large; somewhat narrowly but regularl}^ 

 rounded upon the periphery in the adult state, and broadly 

 rounded at the sides; whorls almost completely involute, the 

 umbilici being very small; septa somewhat deeply concave; ven- 

 tral saddles large, prominent, and regularly rounded; lateral 

 lobes broad and moderately deep; lateral saddles prominent and 

 narrow, and rounded at the outer end, and also becoming later- 

 ally prominent in the later formed septa of adult shells. The 

 character of the surface is unknown, but it is apparently plain; 

 and the test was moderately thin. In the young state the shell 

 was more globose in form, and the septa were much less deeply 

 lobed. 



"All the specimens which have yet come under my observa- 

 tion are in the condition of natural casts, and all are imperfect. 

 The best one of these specimens is figured on plates VII, VIII 

 and IX, [represented herewith by Pis. 13, 14,15] together with 

 a fragment showing the inner volutions. The outlines which 



