THE EYE-MUSCLES. 225 



brevis in most cases enters the eye-ball with or near the 

 optic nerve. To this Menidia is a conspicuous exception. 

 The fact that fibres of the radix longa can be followed 

 through the ciliary ganglion, while those of the radix 

 brevis cannot, accords with the physiological results of 

 Langley and Anderson ('92) and with the degeneration 

 experiments of Apolant ('96; cf. also Huber, '97, pp. 124, 

 125). 



Summary of Section 8. 



The sympathetic nervous system so far as studied con- 

 forms in the main to previous descriptions, and most 

 closely to Stannius' account of it in Belone. The "head 

 part " contains six important ganglia, aside from the 

 ciliary. These are related to the roots of the X, IX, VII, 

 V and III nerves. The radix longa of the ciliary gan- 

 glion is accompanied by general cutaneous fibres which 

 arise from a special projection of the Gasserian ganglion 

 and were traced into the ciliary ganglion. These fibres I 

 have homologized with the r. ophthalmicus profundus 

 trigemini. 



Section 9. — The Eye-Muscle Nerves. 



I.— The Eye-Muscles. 



The eye-muscles themselves merit a brief preliminary 

 description. The sub-cranial canal is greatly developed 

 and within it are the origins of the mm. rectus externus, 

 rectus internus and rectus superior. It originates at the 

 extreme caudal end of the basioccipital (Fig. i, s. c), runs 

 forward as a round canal at first within that bone, pro- 

 gressively expanding until farther cephalad it becomes 

 broadly triangular in cross-section, the base of the triangle 

 being dorsal. (Fig. 2). The floor of the canal is here 



