550 GKOHGINA SWEET. 



covers the front of the eye, immediately beneath the skin, 

 instead of lying beneath the muscle and connective tissue as 

 in Notoryctes. 



Muscles. 



In the posterior small end of the fibrous capsule are to be 

 found the bands of muscle (fig. 1, m.) which represent the 

 degenerated eye-muscles, being attached posteriorly to the 

 wall of the skull. There are four constant muscles usually 

 lying beneath the eye mass. Often there is a fifth slip of 

 muscle, separated off from the upper and most external one 

 of these, which very early becomes attached to the pyriform 

 fibrous capsule around the eyeball. The other four continue 

 forwards for a varying distance (fig. 1), sometimes stopping 

 behind the level of the pigment ball, sometimes, but rarely, 

 extending to the level of its anterior border. Invariably, 

 however, they end in a more or less broken or irregular 

 fashion in the outer fibrous capsule, or rarely within it, 

 amongst the connective tissue, which is variable in quantit3\ 



Variations are met with in the proportionate length of this 

 hinder muscular region. Most frequently it is merely one 

 sixth of the total length, in which case the gland mass is 

 larger. In several instances the muscles are one half to 

 two-thirds the length of the capsule, the gland being then 

 proportionally smaller. At the extreme posterior end of the 

 capsule there enters an arterial twig from the internal 

 carotid, which appears to supply these muscles. At the 

 anterior part of this muscular region there leaves the capsule 

 a large vein, which runs downwards and outwards to join the 

 facial vein. 



These muscles are, in contrast to those of Mammalia gene- 

 rally, of the non-striated kind, resembling them in size, 

 shape, character of the nuclei, and apparent absence of 

 sarcolemma. As far as can be seen those which are external 

 and inferior in the present condition are, as a rule, larger and 

 run the farthest forward, in other words, degenerate last. 



