1894.] Geology and Paleontology. 415 
“The uplift and metamorphism of the Sierra Nevada and of the 
Coast range occurred in late Jurassic time, before the deposition of the 
Cretaceous.” 
“ Neumayer’s theory of climatic zones cannot be applied with exact- 
ness to the Jura of California, which can be understood’ only by the 
study of the geographic provinces of that time.” (Bull. Geol. Soc. Am. 
Vol. 5, 1894.) 
Comparison of Jurassic and Upper Cretaceous Trituber- 
culates.—In a paper on upper Cretaceous Mammals, Prof. Osborn 
makes the following comparison of the Laramie mammalian dentition 
with that of the earlier Purbeck, and of the later Puerco. 
“ In the Laramie the modern placental or marsupial dental formule 
are established—the teeth behind the canine are usually seven, and do 
not usually exceed eight. Marsh observes in one jaw what he considers 
five premolar alveoli. Second, out of the high crowned upper molars of 
the Jurassic, such as those of Amblotherium and Spalacotherium, a 
relatively low-crowned or bunodont tritubercular molar has been 
evolved ; as this is a possible parent form of the ungulate and primate 
upper molars, it is an essentially Tertiary type. Third, the lower 
molars have evolved a broad talonid or heel, which in many cases pre- 
sents three cusps, whereas in Jurassic types the talonid is a spur or a 
narrow simple basin. Fourth, the trigonid, which is always very 
elevated in the Jurassic types, sinks in some cases to the level of the 
Talonid—another modernization looking toward ungulate and primate 
“ Two features make the Laramie fauna appear more ancient than 
the Puerco : first, the non-development of an internal cingulum, which 
is common in the Puerco; second, the entire absence of the hypocone, 
which is quite strong in some Puerco mammals. On the other hand, 
the upper and lower molars of Types represented in figs. F, G, I, Cl, 
respectively, are analogous to Ectoconus, Dissacus, Diacodon, aud 
Haploconus of the Puerco.” 
“The zoological affinities of this fauna are at present hard to deter- 
mine. Ptilodus and Meniscoéssus are still provisionally referred with 
the Multituberculates to the Monotremes. Thlæodon exhibits a jaw 
Without an angle, and with a surprising resemblance to that of Poly- 
mastodon ; the jaw is certainly neither of the typical placental nor of 
the marsupial type; this animal may therefore be provisionally con- 
Sidered a trituberculate Monotreme.” 
