258 Journal of Comparative Neurology and Psychology. 



the formation of the sympathetic gangHa in the Hght of the 

 adult structure, we must suppose that the spinal ganglion cells 

 which migrate to the sympathetic ganglia are those of the gen- 

 eral visceral component. 



It is a striking fact which has not passed unnoticed that 

 the composition of the sympathetic closely resembles that of a 

 branchial nerve minus the cutaneous components of the latter. 

 In cyclostomes and selachians no sympathetic gangHa have been 

 found in the head, except the ganglion ciliare. If this be the 

 true condition then in these forms the cranial ganglia must be 

 considered to contain the equivalent of the sympathetic. That 

 they can not as a whole be considered homologous with the 

 sympathetic ganglia of the trunk is obvious from the presence 

 of taste fibers and general cutaneous fibers. In teleosts (46) 

 sympathetic ganglia are present in connection with the typical 

 ganglia of the profundus, V, VII, IX and X nerves, in addition 

 to the ciliary ganglion which is the sympathetic ganglion of the 

 segment anterior to the profundus. The ganglia are connected 

 by a longitudinal fiber strand as in the trunk. The high develop- 

 ment of the sympathetic in the head of teleosts suggests that 

 it may yet be found in selachians. 



/p. Relation of dorsal and ventral nerve roots to the myotomes. 



In Amphioxus the ventral root emerges from the spinal 

 cord opposite a myotome and enters the muscle directly. The 

 dorsal root emerges from the cord between two myotomes, 

 passes along the myoseptum to the surface and is distributed to 

 the ectoderm overlying the myotome next anterior to its root. 

 I can add from my own observation that although the ventral 

 ramus (the visceral fibers of which do not concern us here) 

 usually passes vertically ventrad and so crosses the surface of 

 three myotomes, it not infrequently happens, especially in the 

 caudal half of the body, that the ventral ramus runs caudo- 

 ventrally at the same angle as the myotomes and a single nerve 

 is confined to the area overlying a single myotome. 



In Ammocoetes by putting together the work of Hatschek 

 (44) and Koi.TZOFF we can account for every one of the dorsal 



