1 50 Journal of Comparative Neurology, 



passes dorsad to muscles, the other caudad and ventro-laterad. 

 The ventral root of the third nerve, which is a complete nerve 

 with dorsal root and ganglion, arises like the first and second. 

 It passes obliquely latero-caudad to leave the canal in company 

 with the dorsal root, which joins its ganglion just ectad of the 

 foramen. The ventral root, lying mesad of the ganglion, di- 

 vides into three parts, each of which is joined by bundles from 

 the ganglion. One passes directly dorsad, the second laterad 

 to break up immediately into a number of branches, while 

 the third and largest division passes directly caudad, fusing with 

 the caudal portion of the ganglion. Fischer's recognition of 

 the first of these nerves as a spinal accessory cannot be agreed to, 

 because of its mode of origin from the extreme ventral aspect ; 

 and its distribution, in part at least, is not comparable with that 

 of the I ith. It is preferred here to speak of these nerves as the 

 first, second and third spinal nerves, although the area of the 

 hypoglossal is supplied from some of their branches. An in- 

 dication of a dorsal root for the first of these has been found by 

 Kingsley ('92) in AnipJiuiuia and by Mrs. Gage ('93) in the 

 larval Diemyctylus. 



GENERAL MORPHOLOGY. 



RJiincncepJial. In the application of this term to the olfac- 

 tO:ry lobes in Nectiirus, it is not the intention to convey a pre- 

 judgement of the interesting problem as to whether or not they 

 are entitled to recognition as constituting a separate segment of 

 the brain. It is possible indeed that the olfactory lobes and 

 the portions of the cerebrum which are associated with the sense 

 of smell, constituting, it is believed, almost the entire second- 

 ary forebrain in the Nectunis, should properly be regarded as 

 representing a single primitive segment, — Rhinencephal. Turner, 

 followed by Schaier and Edinger, who extend the application, 

 has applied the term rhinencephal to such portions in higher 

 forms, not employing it in a segmental sense, however. As has 

 been insisted by Wilder ('93) Rhinencephal used in its true seg- 

 mental sense should include mesal (portion of aula), as well as 

 ventral, portions of the parietes. Mrs. Gage ('93) from the 



