CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
135 
cart-horses; but how they had performed this I am unable to 
say, neither could I obtain any information as to their previous 
soundness or unsoundness. In all these three cases the patho- 
logical appearances were similar. The capsular ligament of the 
joint was healthy in appearance, structure, and points of attach- 
ment ; and on its being removed, and the articular extremity of 
the bone taken out of its socket, no trace of a ligamentum teres 
could be seen. The depression on the head of the thigh-bone, to 
which it is usually attached, did not exist, and the cartilage of 
incrustation formed a uniform covering to it. The depression in 
the cotyloid cavity was filled up as usual by the Haversian 
gland ; the cotyloid ligament was well formed, and, if any thing, 
larger than usual ; but at the notch in the cotyloid cavity, where 
its fibres proceed to form the round ligament, no traces of an inter- 
articular band existed, nor was there any preternatural attachment 
of the capsule to the cotyloid ligament at this point, so as to 
compensate for the absence of the round ligament. The whole 
of the inside of the joint had a uniformly smooth surface : the 
synovial membrane was healthy in appearance, and the synovial 
fluid was natural in quantity; and the movements of the joint 
seemed to have been perfectly performed, and without tendency 
to dislocation and consequent lameness.” 
It is perfectly evident to me, therefore, from the above report, 
that these were instances of congenital deficiencies of the round 
ligament; and, as such, it might naturally be asked, Could not 
spontaneous dislocation occur, and consequent lameness be the 
concomitants of such a state of parts ] So far as negative reason- 
ing goes, I should be inclined to the contrary, and should rather 
suppose that such a state of parts may exist without giving rise to 
hip-joint lameness to any extent. 
As the above pathological appearances are the same as those seen 
in the human individual under similar circumstances, I need not 
direct attention to these latter cases, and shall therefore proceed 
to consider the last and most extensive form of congenital mal- 
formation. 
IY . — Arrest in the Development of the Neck and Head of the 
Thigh Bone , with a corresponding Deficiency in the Develop- 
ment of the Cotyloid Cavity. 
This form of arrested development is the most extensive in its 
nature, and the most serious in its consequences, on the functions 
of the articulation, of any of those which have been enumerated. 
It is by no means a very frequent occurrence in the human indi- 
vidual, though it has been sufficiently so to attract the attention of 
