TRANSACTIONS OF SECTION D, 731 
socket-joint; the stem is stayed hy ligaments. In sharks it dwindles into a 
slender rod, and is absent in some. Its origin was found to be by an independent 
chondrification within the mesoblast packing of the orbit, 
The eyes of many bony fishes are supported by a ligament in close relation to 
the optic nerve. The occurrence of the ligament was very frequent in fresh-water 
fishes. 
(3) Musculature.—The eye-muscles of fishes are singularly uniform in their 
relations, Among the variations found may be noted that in Zygena Maleus 
The short M. recti are attached to the distant basis cranii by means of a long 
common tendon. 
Provision for projection and retraction of the bulb was found in a few cases, 
the special movement of the eyes of Feriopthalmus koelreuteri is probably not of 
this nature; but of elevation and depression. 
The formation of palpebral retractors by a superficial delamination of the 
M. recti was noted in some cases. 
A special form of M. obliquus superior was found to exist in both eyes of all 
pleuronectids, which provides for the rotation of the eye. This muscle consists 
here of two parts, one like the normal M. obliquus superior of other fish, a second 
in a long, slender, strap-like portion, which embraces the upper and outer qua- 
drant of the bulb. The axis of vision of these fish can be noted to be frequently 
in a state of convergence; it is particularly interesting to note this specialisation 
in this connection, since like conditions of the muscle are found in animals 
possessing the capacity of convergence of visual axes, e.g. horse and man. ‘This 
indicated the possibility of independent evolution of organs in widely severed 
types along similar lines when the conditions of use are similar! 
4, The Pelvic Symphysial Bone of the Indian Elephant. ‘ 
By Professor R. J. ANDERSON. 
The symphysial cartilage of many mammals is often converted into bone. 
Numerous examples have been noted and commented on by myself and others. It 
is only necessary to refer to the fact that ligaments are often converted into bone. 
The tentorium cerebelli of certain carnivora, the ligaments of the pelvis (sacro- 
sciatic) in the sloth and armadillo, the tendons in the leg of the turkey,-the supra- 
scapular ligament in man, and the-abdominal fibrous bands in the crocodile, are 
the often-cited examples of bones that are developed in tendinous or membranous 
structures. 
The symphysial cartilage or bone has been, in the pelvis, regarded as the 
equivalent (homologous to the whole or part) of the sternum, and has been called a 
pelvisternum. Whether this be so or not, the actual condition of the bone is of 
considerable morphological interest. 
Mr. Schliiter of Halle supplied to our Museum three years ago the rough skele- 
ton of an elephant. When cleaned and mounted, it appeared to have been about 
eight feet high at the shoulder. The ischio-pubic epiphyses are still separate, and 
the iliac crest, still incomplete, is not united to the ilium. The head of the femur 
and the great trochanter are not united to the shaft of the thigh-bone. 
A wedge-shaped bone exists between the pubes of opposite sides, the anterior 
surface is triangular, is two and a half inches in height, and one and a quarter inches 
wide This surface is convex from below upwards. The lower surface, which is 
keeled, is two and a half inches in length. The bone tapers posteriorly. 
The skeleton of the elephant in the National Museum of Ireland has a small pelvic 
symphysial bone, and the camel in the Museum of the Royal College of Surgeons 
of Ireland has also a well-formed example of the same bone. Many skeletons have, 
however, been so well (?) cleaned that the symphyses have disappeared. 
* It is not easy to account for the symphysial cartilage or bone morphologically, 
' The paper has been published in extenso, with plates, in the Jowrnal af Anatomy 
and Physiology, Nov. 1899, vol, xxxiy. p, 1. : 
