4, 
ORDERS OF MAMMALIA. 
* Young not born until of considerable size, and nearly perfect development, deriving 
its nourishment before birth from the blood of the mother through the intervention 
of aplacenta; vagina a single tube, sometimes with a partial septum ; cerebral hemi- 
spheres connected by a well-developed corpus callosum and a reduced anterior com- 
missure. (Sub-class Monodelphia.) 
t Brain with a relatively large cerebrum, behind overlapping much or all of the cere- 
bellum, and in front much or allof the olfactory lobes; corpus callosum continued 
horizontally backwards to or beyond the vertical of the hippocampal sulcus, develop- 
ing in front a well defined recurved rostrum. (Super-order Educabilia.) 
Anterior and posterior limbs and pelvis well developed; legs with the proximal joints 
(humerus and femur) not exserted beyond the common integument of the body. 
a. Digits with corneous appendages developed as claws; teeth of three kinds; 
canines specialized and robust; molars, one or more in each jaw, sectorial, 
adapted for cutting ; incisors + ; scaphoid and lunar bones consolidated, 
placenta deciduate and zonary. : : : : ° CARNIVORA. 
aa. Digits with corneous appendages developed as hoofs; teeth of three kinds; 
incisors various, often reduced or wholly suppressed, especially in upper 
jaw; no developed tusks; scaphoid and lunar bones separate; placenta 
non-deciduate (diffuse or cotyledonary.)  . : . . UNGULATA. 
tt Brain with a relatively small cerebrum, leaving behind much of the cercbellum ex- 
posed, and in front much of the olfactory lobes; corpus callosum extending more or 
less obliquely upwards, terminating before the vertical of the hippocampal sulcus; 
no well defined rostrum in front. (Super-order Ineducabilia.) 
b. Incisors (very variable in number without persistent pulps) never 5 ors 3 
canines present; molars with sharp and pointed tusks; lower jaw with 
condyles transverse, received into special glenoid sockets. » 
ce, Anterior limbs adapted for fiight; ulna and radius; united}; bones of hand 
and finger much elongated, supporting a thin, leathery skin extending 
along sides of body to the posterior limbs; mammz pectoral. 
CHEIROPTERA. 
cc. Anterior and posterior limbs adapted for walking or grasping; ulna and ra- 
dius entirely or partially separated; bones of hand and fingers normally 
developed; mamme abdominal. : : 6 6 INSECTIVORA. 
bb. Incisors ¢ rarely +; continually produced from persistent pulps, and growing 
in a circular direction; canines none; molars with ridged surfaces; lower 
jaw with condyles longitudinal, not in glenoid cavities, but gliding freely 
backwards and forwards in longitudinal furrows. . . RODENTIA. 
** Young born of very small size, and imperfectly developed, never connected by a 
_ placenta to the mother; when born, attached by her to the nipple, from which the 
4" milk is forced by the mother into the mouth of the young; cerebral hemispheres 
chiefly connected by a well-developed anterior commissure, the corpus callosum 
being rudimentary ; vagina more or less completely dividing into two separate 
passages. (Sub-class Didelphia.) ; : : : ° . MARSUPIALIA. 
