258 GENERAL CONSIDERATIONS. 



cate fibres pass into the cirri themselves. Other branches of these same cerebral 

 nerves, though apparently independent of the atrial ganglia, pass to the anterior 

 end of the body where they doubtless innervate the body wall including the 

 hypodermis. In Pachymenia abyssorum and Dorymenia acuta the body wall 

 of the anterior end of the body (and possibly the atrial ganglia, cirri, and atrial 

 ridges) is also supplied with nerves from the anterior end of the lateral ganglia. 

 In Dorymenia acuta nerves from the anterior end of the pedal cords and from 

 each anterior latero-pedal connective have been followed to the external atrial 

 ridge. The pharynx is supplied, at least in part, with nerves from the labio- 

 buccal ganglia or from some of the labiobuccal connectives, and in Dorymenia 

 acuta a pair of small nerves, having an independent origin from the sides of 

 the brain, have been followed a short distance into the pharyngeal musculature. 

 In Alexandromenia agassizi and Pachymenia abyssorum the walls of the out- 

 let of the anterior pedal gland are fiirnished with nerves from the anterior end 

 of the pedal ganglia. 



The dorsal side of the body is supplied Avith nerves from the lateral cords, 

 the sides are furnished with branches from the lateral and pedal ganglia and to 

 some extent by dehcate offshoots from the latero-pedal connectives, while the 

 ventral surface is innervated by nerves from the pedal cords. In rare instances 

 slender branches from the pedal commissures have been followed into the foot 

 or ventral fold. In the posterior end of the body the terminal section of the 

 shell gland or ventral section of the coelomoducts in Slrophomenia ophidiana and 

 Alexandromenia agassizi are suppUed with nerves from the posterior end of 

 the pedal gangUa or from the posterior latero-pedal connective in Drepanomenia 

 vatnpyrella. Nerves to the pericardial wall and heart in Stropho^nenia ophidiana 

 have their origin in the posterior end of each lateral ganglion. Nerves from 

 the same source enter the gill lamellae in Pachymenia abyssorum and Alexandro- 

 menia agassizi which in the first named species at least are also innervated by 

 other nerves from the posterior end of the pedal ganglia. The body and cloacal 

 walls are furnished with nerves from the posterior end of the pedal and lateral 

 cords and in Drepanomenia vampyrella an additional supply originates in the 

 most posterior latero-pedal connective. In several species the suprarectal 

 commissure gives off one nerve (two in Strophomenia regxdaris) which enters 

 the dorso-terminal sense organ. In Alexandromenia agassizi the nerve to the 

 sense organ is a relatively small offshoot of a branch having the usual attach- 

 ment to the suprarectal commissure, but more posteriorly it passes into some 

 of the more dorsally placed gill lamellae. 



