AVES. 115 



their transverse processes, long and slender, being directed downwards and 

 forwards ; the articular processes are almost as prominent as the neural spines, 

 the prominent portions being termed the mammillary processes (meta- 

 pophyses), and they may be traced anteriorly into the dorsal region ; they 

 give attachment to portions of the longissimus dorsi muscle. The anterior 

 costal tubercles, prolonged and sharpened, likewise afford attachment to that 

 muscle. The sternebrce are five in number, the presternum being very long 

 and cariniform in shape. 



In the skull we note the unusual length of the zygomatic process of the malar 

 bone, and absence of a frontal arch, which is represented by a short bifid process. 

 The optic foramina unite to form a single passage leading from one orbital 

 fossa to the other. The diastema and incisive openings are both very laro-e 

 and laterally the superior maxilla is incompletely ossified, giving an irregular 

 cribrated appearance to the bone ; the bony palate is exceedingly short. The 

 auditory bulla and external meatus are well marked. The long axis of the 

 maxillary condyle is placed longitudinally, and the coronoid 2^i'ocess is very 

 small and far below the level of the condyle, whilfe at the angle of the jaw 

 there is a prominent roughened ridge or spine. There are no canine teeth, 

 and two chisel-shaped incisors exist in each jaw ; in the upper jaw of the 

 rabbit and hare there are also two very small incisors placed immediately 

 behind the large ones. 



Appendicular Skeleton. 



The scapula has a very large acromion process which projects backwards, 

 arching over the postea-spinatus fossa. There is a small clavicle, but it is 

 incomplete. The coronoid and condyloid foss£e of the humerus are connected 

 by a foramen. The ulna is complete, reaching to the carpus, but there is no 

 motion between it and the radius, and the extremitj^ is therefore prone. There 

 are five digits, one of which represents the pollex or thumb. The velvis is 

 broad and shallow, the ischial arch deep, and the obturator foramen larcfe. 

 The femur has, like that of the horse, a third or minor trochanter ; also two 

 well-marked fabellas. The tibia and fibula are anchylosed, the former bone 

 being very long. The astragalus resembles that of the carnivora. There are 

 five digits, including the hallux. 



AVES. 



The scope of the present work will allow only very brief treatment of this 

 part of the subject. We shall, therefore, merely name a few of those features 

 in which the skeleton of the bird diflers in a marlced manner from the 

 mammalian type. 



The vertebrae vary greatly in number, the cervical in some classes number- 

 ing over 20, and never less than 8. Small cervical ribs exist in the young 

 animal, which in age may become anchylosed to the vertebrae, and in the 

 dorsal region osseous splints unite the successive transverse processes. On the 

 posterior edge of each rib, except the first and last,, is a process called the pro- 

 cessus uncinatus, which overlaps the succeeding rib. The sternum is a single 



