INTRODUCTION. 17 
Spee. 1. Spee. 2 Spec. 3 Spec. 4 
Phosphate of iron : a 2He.O. 3 bO; 2.821 
- magnesia . 3MgO,PO, 0.770 2.099 0.403 0.98 
« lime ’ . 8Ca0,PO, 69.685 68.582 83.835 77.81 
i. soda : . 2Na0;PO, 1.415 1.079 1.413 —. 
Sulphate of baryta ; . BaO,SO, 0.547 1.723 — = 
fe soda 2 . NaO,SO, 1.083 2.443 1.437 ileal 
a potassa. = KOSO: 5: 0.587 0.510 0.442 0.43 
" lime : . C€a0,SO, 0.60 
Silicate of lime . : . 38CaO,SiO, 0.382 0.732 1.727 2.23 
Carbonate of lime : 2p C20; CO, 9.315 5.172 7.212 6.45 
Lime . 5 : ‘ . CaO 6.605 6.517 1.284 2.35 
Fluoride of calcium . Caf 0.716 5.086 0.099 2.90 
Water ¢ c : ELO 2.048 1.971 0.626 2.10 
Organic matter. : 5 : ‘ : 5.682 4.086 2.538 2.66 
101.656 100.000 101.016 100.223 
Cuvier, in speaking of the remains of mammalia in the gypsum quarries of the 
Paris basin observes, “on peut s’étonner que dans une contrée aussi étendue que 
celle qu’occupent nos carriéres, et qui a plus de vingt lieues de lest & Youest on 
n’ait presque trouvé que des os d’animaux d’une seule famille, et que le petit 
nombre d’espéces étrangéres 4 cette famille principale, y soient d’une rareté ex- 
tréme.” The distinguished author infers from this a condition analogous to that 
presented in our day by Australia. More recent researches, however, have shown 
that in the single family alluded to, the Puchydermata, he included members really 
belonging to one of the other Cuvierian families; for the Anoplotherium and Di- 
chobune are now generally considered to have been true ruminating animals. 
With a single exception, all the species of extinct mammalia, which have yet 
been obtained from Nebraska, belong to the Ungulata, and, as in the case of those 
of the Paris basin above referred to, consist of Ruminantia and Pachydermata. 
The great order of Ungulata, or hoofed mammalia, according to the idea originally 
expressed by Cuvier, and confirmed by De Blainville, but more especially by Owen, 
is divisible into two distinct sub-orders, the Puridigitata or even-toed ungulates, and 
the Imparidigitata, or uneven-toed ungulates. 
The sub-order Puridigitata may be divided into the families Ruminantia and 
Ordinaria. 
The Ruminantia are further divisible into sub-families as follows :— 
1. Those which are hornless, and have incisors and canines in both jaws; as 
Anoplotherium, Macrauchenia, Dichobune, Chalicotherium, ete. 
2. Those which are hornless, and have canines and an incomplete series of in- 
cisors or none at all, in the upper jaw; as Camelus, Auchenia, Moschus, Dorcathe- 
rium, ete. 
3. Those which have processes of the os frontis, or have antlers, in one or both 
sexes, and have or have not upper canines, or have them in a rudimentary con- 
dition, and which are without upper incisors; as Cervus, Cameloepardalis, ete. 
1 Proc. Acad. Nat. Sc., VI. 292. 
