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. 

 Mammae two, pectoral. — Heart deeply fissured between the ventricles. 



SIRENIA. (VII.) 



. Brain broad. Skull with the foramen magnum entirely posterior, 

 directed somewhat upwards: supra-occipital very large, sloping for- 

 wards, and (attypically) 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 

 corouoid processes. Teeth conic or compressed, monophyodont. Neck 

 attypically very short; second cervical vertebras 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. Mamma? two, inguinal. 



CETE. (Vm.) 



II. 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. 



SUPER-ORDER INEDTJCABILIA. 



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. Mamma? pectoral. 



CHIROPTERA. (IX.) 



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. Mamma) abdominal : 

 (etypically — in Dermoptera, &o. — pectoral). 



July, 1871. mSEGTIYORA. (X.) 



