130 CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
On analysing the various congenite malformations of this joint, 
it will be found, that the deficiency in each case will vary very much, 
and, consequently, that the functions of the articulation will be more 
or less diminished or destroyed, according to the nature and extent 
of the loss. Hitherto all these conditions have been described 
under the general head of “ congenital malformation,” without any 
distinction as to the extent of their deficiency ; but in the following 
remarks I have endeavoured to arrange these, as far as possible, 
according to the nature and extent of the arrested development, in 
the hope that they may be of some use in conducting the inquiries 
of other observers. 
As the subject is almost new to veterinary literature, I have 
thereby been necessitated to draw many of my illustrations from 
human pathology; but, as the barrier between human and com- 
parative pathology is every day becoming less and less, and as 
the influence of those agents, that operating in man, produce certain 
diseases and certain pathological effects, and, in the lower animals, 
induce the same, are becoming daily more and more admitted and 
substantiated, then it will be granted by every pathologist that the 
pathology of the one class will be that of the other. 
In the following remarks, I have arranged the various congenital 
malformations of the joint under four divisions, each differing from 
the other in the extent of its deficiency : first, deficiency in the 
capsular ligament; secondly, elongation of, or misplacement in, the 
attachment of the round ligament; thirdly, absence of the round 
ligament ; and, fourthly, deficiency in the cervix and articular head 
of the thigh bone, with a corresponding deficiency in the cotyloid 
cavity. 
I. Deficiency in the Capsular Ligament of the Joint, and the Arti- 
cular Synovial Membrane, communicating with the Cavity of the 
Bursa , beneath the Psoas Magnus and Iliacus Muscles. 
The simplest form of deficiency of structure, in this or any other 
of the articulations of the body, consists of a congenital want of 
continuity of the peripheral investment, the capsular ligament. 
This condition of the joint, however, has scarcely been noticed by 
pathologists as being a positive congenital defect ; for, when dis- 
closed by dissection, it is often extremely difficult to decide, as to 
whether the appearance must be viewed as a congenital deficiency, 
or the result of some injury, inducing dislocation of the head of the 
thigh bone, and consequent rupture of the ligament. I have not 
met with this state of the articulation in the lower animals, but I have 
seen one instance of it in the human body, in the person of an adult 
female, and where there was every reason to suppose that it was 
