146 NEW YORK ZOOLOGICAL SOCIETY. 



frequent in the straight-backed monkeys (see pkite 2) as in 

 these whieli ]iresenl a ncnnahy eurwd s])inal enhinm. The 

 position, already descril)(.(l. whicli the animal earl\ begins to 

 asstime is tlotibtlcss largely responsible for this very marked de- 

 formity. 



The thorax presents some of tlie most typical malformations. 

 The lower ribs generally become more widely se])arated, while 

 the upper ones, particularly those to which the pectorals are 

 attached, become liowed in, sometimes forming a peculiar letter 

 S deformity (see plate 3). Ordinarily this causes a throwing 

 forward of the sternum, jiroducing in some cases a ty]Mcal "pigeon 

 breast" (see plate 3). The points of juncture of the ribs with 

 the costal cartilages beconu' enlarged, causing nodes like those 

 tvpicallx seen in rachitis (the "rachitic rosary"). Special types 

 of deformity of the thorax may be seen, depending largely on 

 the ])hvsical habits of the ])articular animal and on the character 

 of the sjjinal column deformity. 



The bones of the lower extremity are usually more or less 

 deformed, ununited fractures may be ])reseut. surround(,'(l by un- 

 calcified fibrous callus. As a rule, an outward lateral curvature 

 is presented, but on account of the early ])aralysis and since the 

 animal verv soon learns to support itself on the ui)per extremities, 

 swinging the body between the arms as in tising crutches, the 

 relief of weight from the lower extremities doubtless prevents 

 extreme deformit\- of the bonrs. In our opinion the l)ony 

 changes are inaugurated in thr bont's of the lower extremities, 

 if we ma\' judge from the s\]ni)to;ns tlrst manifested and from 

 the earliest develoimient of deformity. The ends of all the long 

 bones frequentl\' become enlarged. 



Changes in the pelvis are not ver\- marki'd and. as a rule, the 

 form is fairly well ])rrserved, but, conse(|ui'nt u])on deviations 

 of the column, various lateral deflections may be seen. The most 

 frequent (Kformit\-. while not reall\- one of the ]K'lvis itself, is 

 the development of an unusuall\ acute angle at the juncture with 

 the lumbar and sacral colunm. 



Deformities in the n])i)er extremities are not usually jiresent. 

 except for increase in size of the epyphyseal ends of the bones 

 and. as a rule, these a])iiear rather late in the disease. This is 

 probably (\uc to the fact that involvement of the upper extremities 

 of the animal are among the very later stages of the disease, and 

 ordinarily before tin- animal has i)rocceded sr) far he has either 

 succumbed tc) the terminal i)roeesses or. ha\-ing bci-mnc unfit for 

 exhibition, has Ijeen killed. 



