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Bdellostoma are the homologues of the palatinus facialis of Amia, 

 they must be largely communis nerves; which would seem to be in 

 accord with the origin ascribed to them by v. Kupffer, in relation 

 to certain of the epibranchial ganglia. 



From the posterior portion of the maxillo-mandibularis ganglion 

 two nerves arise, one from its dorso-posterior portion, and the other 

 from its ventral surface. The dorso-posterior nerve runs laterally and 

 forward across the dorsal surface of the pterygo- quadrate, immediately 

 posterior to the eye, and goes directly to the skin. It is accom- 

 panied by, and in part of its course encloses, an artery exactly 

 resembling in this the nerve that I have described as the ophthalmicus 

 lateralis. Having reached the skin (Fig. 1) it runs forward and 

 downward along its inner surface, breaking up into several branches 

 exactly as the ophthalmicus lateralis does. It would therefore seem 

 to be the homologue of the buccalis facialis of the gnathostome Ich- 

 thyopsida, but it is to be especially noted that it does not arise from 

 the same ganglion and root as the ophthalmicus lateralis, and that it 

 does not issue from the trigemino-facialis chamber with the ramus 

 maxillaris superior trigemini, or in any way accompany that nerve in 

 its peripheral course. It is the posterior, upper cutaneous branch (5*) 

 of the ophthalmicus trigemini of Müller's descriptions of Bdellostoma 

 heterotrema, that nerve being considered by that author as an oph- 

 thalmic nerve, notwithstanding its evident position below the eye, and 

 hence necessarily ventral or posterior to the nervus opticus. Für- 

 bringer (9) shows the corresponding nerve in Myxine glutinosa run- 

 ning forward over the opticus, and the "trunk of the ophthalmicus" 

 running forward below the opticus; which almost leads one to believe 

 that he here has, first in his figures and then in his descriptions, 

 simply transposed these two trigeminal nerves in their relations to the 

 opticus. 



The buccalis lateralis, thus identified, is evidently the nerve f of 

 v. Kupffer's descriptions. That nerve is said by v. Kupffer to 

 arise, in embryos, from the ventral surface of a separate ganglion, 

 C\ and to separate at once into three branches, all of which go to 

 regions of the skin where lateral sensory organs later develope. 

 v. Kupffer accordingly considers these three branches of the nerve 

 as the ophthalmicus, buccalis, and oticus facialis. He does not say 

 whether the ramus ophthalmicus facialis runs dorsal or ventral to the 

 opticus, but it would seem, from the descriptions, to lie ventral to it ; 

 which it could not do if it were the homologue of the similarly named 

 nerve of the gnathostome Ichthyopsida. 



