CRANIAL NERVES OF CHIMERA MONSTROSA. 643 



The ciliary ganglion. — Soon after its origin the ventral or deep branch of the oculo- 

 motor gives off a fine nerve — ultimately found to be the radix brevis (see fig. 1). 

 This is joined by a similar nerve, arising from the profundus just distal to its ganglion, 

 which is thus seen to be the radix longa. These two bundles unite, and at the point of 

 union there is a swelling containing distinct ganglion cells, which will therefore be the 

 ciliary ganglion. From the ciliary ganglion, ciliary nerves with the characteristic wavy 

 course, of which I found two, proceed to the eye. Other ciliary nerves arise from the 

 trunk of the profundus itself. Although this account agrees with what Ewart describes 

 in Lsemargus, which is what one would expect to find, I prefer to leave the question 

 open, as I only dissected the ciliary ganglion on one side, and then, owing to the parts 

 having been disturbed by previous dissection, not as carefully as I could have wished. 



Literature. — The Illrd nerve of Chimsera is figured but not described by Stannius 

 (6, Taf. I.). This author, however, did not figure the roots, nor the branch to the 

 inferior rectus, and, further, was erroneous in making the profundus nerve enter the 

 orbit by the same foramen. Schwalbe also (23) gives a similar figure, and evidently 

 follows Stannius, in so far as he too neither describes nor figures the abducens. 



When 1 wrote my preliminary paper I was not aware that the ciliary ganglion of 

 Chimsera had already been described by Schwalbe (23). Having since that time read 

 Schwalbe's important memoir, I find that he gives two figures of Chimsera, and there 

 is also a short description in the text. Fig. 3, Taf. XII. is a magnified view of the 

 ciliary ganglion, whilst fig. 12, Taf. XIII. shows the nerves of the orbit and the exact 

 position of the ganglion. Schwalbe states that the ganglion is situated on the 

 ventral ramus of the oculo-motor at the base of a ciliary nerve, and 9 mm. distal to the 

 spot where the branch of the ventral ramus to the inferior rectus muscle is given off, and 

 is visible as a distinct swelling. (The position of the ganglion, with its ciliary nerve, is 

 shown in fig. 1). I accordingly mounted the whole of the ventral ramus of the oculo- 

 motor on a slide, and found that whilst there was certainly no swelling, or any traces 

 of one, a few ganglion cells (not more than 20) were situated on the anterior edge of 

 the nerve at the base of a ciliary twig, and at the precise spot mentioned by Schwalbe. 

 Whether Schwalbe's ganglion and my own are both present must be left for future 

 investigation to determine, but I may mention that Krause * believed in the existence 

 of two ciliary ganglia, and Beard (39, p. 575) says : " from what one sees in sharks, a 

 division of the ciliary ganglion into two ganglia in some cases is not out of question." 

 The latter author, however, describes the ciliary ganglion as being situated on the inferior 

 oblique division of the oculo-motor, thus giving support to Schwalbe's account, whilst 

 Ewart's observations (57) go to show that a double ciliary ganglion is not improbable. 



The Patheticus, or Fourth cranial nerve. — This arises, as in all vertebrates, from 

 the anterior extremity of the roof of the Sylvian aqueduct, or valve of Vieussens, and 



* Morph. Jahr., Bd. vii., 1880. 



