APPENDIX. 575 



•matsr is set free as in the first operation, and raising it with the left 

 hand, the adhesions by which it is yet fixed to the vault of the cranium, 

 adhesions chiefly composed of the veins of the brain, which disgorge 

 themselves into the sinuses of the dura mater, are divided by the scissors 

 held in the right hand. Break down the adhesion in the ethmoidal fossa 

 with the point of the scalpel, detach the olfactory lobes, and the mass of 

 the brain is then set quite free. This proceeding is an operation more 

 difficult than the first, but it has many advantages, preserving intact not 

 only the pituitary gland, but also th^ ethmoidal lobes ; and the ganglia 

 of the cranial nerves are exposed as distinctly as the nerves themselves. 

 Having thus described the means of removing the brain from its osseous 

 cavity, it is enough to state here that in order to study its structure 

 with advantage, it will be well to have two brains, hardened hj soaking 

 for a week or more in alcohol, or in water having a little nitric acid 

 added to it (1 to 20), so as to contract the nervous substance, and make 

 more apparent the outline of the cavities of the brain. 



No. II. 



ON A SUPERNUMERARY OBLIQUE MUSCLE OF THE 



EYEBALL. 



By Thomas Strangeways, Professor of Veterinary 

 Anatomy, Edinburgh. 



(Journal of Anatomy and Physiology^ second series, No. II., May, 1868.) 



A FEW days ago, when dissecting the muscles of the eyeball of an ass, 

 in the dissecting room of the Veterinary College, I was somewhat 

 astonished at finding a small but well-defined muscle, situated between 

 the superior and inferior oblique muscles. It originated by a delicate 

 tendon from a minute depression, in the superior part of the orbital 

 plate of the frontal bone, about midway between the origin of the 

 inferior oblique and the loop or pulley through which the belly of the 

 superior oblique passes. The tendon of origin was succeeded by a 

 fusiform fleshy belly of about three lines in diameter, and about an inch 

 in length, which passed obliquely upwards and outwards on the outer 

 side of the external rectus. The belly, embedded in a quantity of 

 adipose tissue, terminated in a thin, flat tendon, which, after running 

 nearly parallel for a short distance wiUi, and loosely attached by cellular 



