84 



ANATOMY OF AMPHIOXUS. 



segment of the body. Dorsal and ventral roots are entirely 

 independent of one another, and at no point do they coa- 

 lesce as they do in the Craniota. In further contrast to 



cu 



cna? 



Fig. 42 A. — Innervation of tlie region of the oral hood and snout. (After 

 Hatschek, .slightly altered according to the statements of \'.\\ WifHE.) 



ch. Anterior end of notochord. ci. Buccal cirri, fwi, en-. Fu'st and second 

 cranial nerves with their peripheral ganglia, cu. Rami cutanei dorsales. l.h. Left 

 half of oral hood. r.li. Right half of oral hood. 0. 01factor\' pit. sf^. sf-. First 

 and second dorsal spinal nerves, so. Sense-organ of oral hood (groove of Hat- 

 schek) indicated as if seen through liod\'-well bv transparency. Z'. \'elum. 

 1'.//./. Nerve to left side of velum, v.ii.r. Nerve to right side of velum. 



N.B. — The septa between the myotomes are indicated by dotted lines. The 

 su()erficial nerves of oral hood are rendered in black; the deeper nerves, which 

 anastomose to form the plexus of Fusari. are left white. 



the condition met with in the latter there is no ganglionic 

 enlargement on the dorsal root. 



