968 MRS. O. A. MERRITT HAWKES ON THE [DeC. 11, 



between the optic lobes and runs outwards and slightly upwards 

 to pass into the orbit through its own foramen. In the orbit it 

 soon divides into the typical three branches, one branch going to 

 the rectus interaus, the second to the rectus superior, and the 

 third dividing into a short and a long branch, of which the 

 former supplies the rectus inferior and the latter the inferior 

 oblique. 



The Recti Siqjerior, Internus, and Inferior are all attached to the 

 top of the optic stalk, just below its flattened head. The rectus 

 superior is a short wide muscle with a narrow attachment to the 

 stalk and a wide insertion upon the eyeball. This muscle is in- 

 serted somewhat to the caudad side of the median line of the eye- 

 ball, and is partly overlapped by the superior oblique and the 

 dorsal division of the rectus externus. The rectus internus is 

 both longer and broader than the rectus superior. It passes 

 under the superior oblique to be inserted on the anterior wall of 

 the eyeball, more to the dorsal than to the internal side. It thus 

 has a somewhat unusual insertioii, and can therefore help in the 

 extra pull given to the dorsal side of the eyeball, when the latter 

 is twisted upwards. It wdll be seen from the figure (Plate LXIX. 

 fig. 4) that the dorsal side of the eyeball has practically four, 

 instead of the usual two muscles. The rectus inferior is longer 

 and narrower than the rectus internus. It has a double attach- 

 ment to the optic stalk, one immediately under the knob and the 

 other, the smaller, at a distance along the stalk itself. This 

 muscle is inserted into the eyeball in the median ventral line, to 

 the inner side of the inferior oblique. 



The eye of Chlamydoselachus has practically three groups of 

 muscles : a dorsal group of four inserted near the angle of the 

 eyeball ; a posterior " group " of one inserted a,lso near the angle; 

 and a ventral group of two elongated muscles three times the 

 length of the dorsal group, acting on the median ventral line, at 

 a distance from the angle of the eyeball. The dorsal group is 

 strengthened to move the eye upwards, while the ventral group 

 merely pulls the eyeball back into the position of rest, and hence 

 does not need to be so powerful. 



E. The Trigemino-pacial Complex. 



The Trigeminal and Facial nei'ves are in parts of their course 

 indistinguishaHe at first sight. This impression, although 

 merely superficial, at the same time undoubtedly expresses a 

 very strong tendency towards the union and confusion of these 

 two nerves. No complete union between the nerves has been 

 found, except for a distance of about 1 cm. on the left side, 

 where a branch of the r. buccalis and of the r. maxillaris are 

 inseparable. The appearance of union occurs chiefly in the 

 region just beyond the orbit, where there are plexiform con- 

 nections between the buccalis VII., mandibularis Y., maxil- 

 laris Y., and their branches. Here, when two or more nerves 



