320 



MISS E. A. FRASER ON THE DEVELOPMENT 



vestiges of the lattei" can only be recognised in the longitudinal 

 series in front of the Gasserian ganglion and just posterior to 

 the ventral side of the anterior portion of the abducens muscle- 

 mass, with which it is no longer connected ; it passes back on 

 the inner side of the root of the maxillary branch of the tri- 

 geminal nerve to join with the maxillo-mandibular muscle-mass. 

 The abducens muscle-mass has not changed in position, except 

 that the posterior dorsal portion does not seem to extend so far 

 backwards, and that the anterior portion has grown out still 

 further laterally (text-figs. 14-16, r.e.). 



Text-fieure 16 



. op.c 





re. tV. v.c.m. 



TricJiosiu-us vulpecida. G.L. 8"5 mm. (IV. '01). 



Horizontal section through the head (S 7-1-4), sliowing- the last vestiges of the left 

 head-cavity {l.h.c.) and the developing m. rectus superior (r..s.). The anterior 

 portion (r.e.) of the abducens muscle-mass lies in front of the vena capitis 

 medialis [v.c.m) and the Gasserian ganglion (ff.V.), and in it lies the abducens 

 nerve (VI.). The ventral edge of the m. obliquus superior (o.s.) is just seen 

 anterior to the optic cup {op.c). X 110 and reduced by^. 



a.c.t. = arteria cerebri anterior. J'5.=fore-brain. w.r. T'.=naso-ciliary branch of 

 the trigeminal nerve. 1 1 1. = oculomotor nerve. 



The oculomotor nerve (text-figs. 14 & 16, III.) again divides 

 at its distal end close to the point of origin of both m. obliquus 

 inferior and m. rectus inferior into many fine fibres, some of which 

 penetrate into the m. obliquus inferior itself (see text-fig. 17, 

 TIL). 



