49 
cervical vertebra with an odontoid process. Anterior members mod- 
erately long, flexed at the elbow; with carpal bones and phalanges 
directly articulated with the adjoining ones; and with normal digits. 
Mamme two, pectoral.—Heart deeply fissured between the ventricles. 
SIRENIA. 
2. Brain broad. Skull with the foramen magnum entirely posterior, 
directed somewhat upwards: supra-occipital very large, sloping for- 
wards, and (attypical'y) extending forwards over or between the 
frontals. Periotic attenuated backwards; tympanic solid, entire. 
Lower jaw with no ascending ramus, with its narrow condyles at the 
posterior extremities or angles of the rami, and with only rudimentary 
coronoid processes. Teeth conic or compressed, monophyodont. Neck 
attypically very short; second cervical vertebra with no odontoid 
process. Anterior members (attypically) abbreviated, extended back- 
wards in a continuous line; with carpal bones and phalanges often 
separated by cartilage; and with the second digit composed of more 
than three phalanges. Mamme two, inguinal. 
Il. Brain with a relatively small cerebrum, leaving behind much of the 
cerebellum exposed, and in front much of the olfactory lobes: corpus 
callosum extending more or less obliquely upwards and terminating before 
the vertical of the hippocampal sulcus; with no well defined rostrum in 
front. 
(VII) 
CETE. (VIII) 
SUPER-ORDER INEDUCABILIA. 
A. Teeth encased in enamel: incisors (very variable as to number) with- 
out persistent pulps: canines present (but sometimes modified in form): 
molars attypically with sharp and pointed cusps. Lower jaw with 
condyles transverse, received into special glenoid sockets. Placenta 
discoidal deciduate. 
1. Anterior members adapted for flight: the ulna and radius being 
united, and the metacarpal bones and phalanges—2 to 5—much 
elongated; the whole sustaining a very thin leathery skin arising 
from the sides of the body, and extending backwards on the hind 
members, down to their tarsi. Mamme pectoral. 
CHIROPTERA. 
2. Anterior as well as posterior members adapted for walking or grasp- 
ing: the ulna and radius entirely or partly separated: metacarpal 
bones and phalanges normally developed. Mammz abdominal: 
(etypically—in Dermoptera, &c.—pectoral). 
INSECTIVORA. 
July, 1871. 
(IX. ) 
(x) 
