ia 
upper part by the medullary artery. Dorso-lumbar vertebrae, generally, 
nineteen in number (d. 12—15+1. 7—4.) Skull with the intermaxillary 
bones flattened above towards the symphysis, and with the incisors, when 
present, diverging towards their roots. Stomach more or less subdivided 
er complex: coecum comparatively small and simple. 
ARTIODACTYLA. 
Il. Digits unpaired or unequal, the third being the largest and most exserted ; 
_ 
(the fourth nearly co-equal in size and position with the second; fifth— 
of hind foot, at least,—atrophied;) the articulating phalanges and carpal 
and tarsal bones correspondingly modified. ‘Astragalus with the anterior 
or inferior articular surface divided into two very unequal facets. Femur 
with a third trochanter, and with its shaft perforated at the back-part by 
the medullary artery. Dorso-lumbar vertebrae not less than twenty-two 
in number (d. 18—19+1. 3—6). Skull with the intermaxillary bones 
tectiform above and united towards the symphysis, and with the incisors, 
when present, implanted subvertically and nearly parallel to their roots. 
Stomach simple: coecum very much enlarged and sacculated. 
PERISSODACTYLA. 
ARTIODACTYLA. 
FAMILIES. 
. Molars (M) attypically each with two double crescentiform folds, whose 
convex surfaces are internal. Canines of lower jaw, attypically, re- 
sembling, and parallel with, incisors; (differentiated and specialized in 
Camelidae). Palatine bones contracted and compressed behind, thin, and 
(at the walls of the posterior nares) separated by a wide sinus from the 
terminal portion of the supramaxillary bones. Digestive system adapted 
for rumination: stomach tripartite, or, attypically, quadripartite, a ‘“ psal- 
terium” being finally developed.—Axis with the odontoid process like 
a spout, or hollow half-cylinder, and with a prominent sharp semi-circular 
rim. (Flower.)—(Pecora; or, Ruminantia.) 
* Incisors deciduous from upper as well as lower jaws. Canines of lower 
jaw inclined forwards, with compressed cuneate crowns. Placenta and 
stomach unknown. Chalicotheroidea. 
One family. CHALICOTHERIIDAE. (XXVII a.) 
** Incisors persistent in lower jaw. 
A. Hind limbs with the proximal joint (femur) exserted and not contain- 
ed within the common integument. Canines of lower jaw specialized 
and differentiated from incisors. Incisors in part (7. e. lateral) persist- 
entinupperjaw. Placenta diffuse. Stomach imperfectly quadripartite. 
(Pecora tylopoda s. phalangigrada.) 
One family. CAMELIDAE., (XXVIII) 
B. Hind limbs with the proximal joint (femur) not exserted but inclosed 
within the common integument. Canines of lower jaw similar to and 
