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 



spi 



spi 



cm 



CJ12? 



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

 HATSCHEK, slightly altered according to the statements of VAN WIJHE.) 



ck. Anterior end of notochord. ci. Buccal cirri. cn l , en' 1 . First and second 

 cranial nerves with their peripheral ganglia, at. Rami cutanei dorsales. l.k. Left 

 half of oral hood. r.h. Right half of oral hood. o. Olfactory pit. s/>\ sf>*. First 

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

 schek) indicated as if seen through body-well by transparency, v. Velum. 

 v.n.1. Nerve to left side of velum. v.n.r. Nerve to right side of velum. 



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

 superficial 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. 



