XIII. Cephalodiscus and Rhabdopleura 



Cephalodiscus. The first report on this animal including a 

 sketch of its anatomy was by Mcintosh, 1887, and later by Lang, 

 1890, and Harmer. Delage and Herouard, 1897, summarize the 

 knowledge of the nervous system about as follows : 



The nervous system is a thickening of the epidermis on the 

 dorsal surfaces of the tentacles. The histological nature of the 

 nervous system was a little studied, but cells and fibers under the 

 epithelium as in echinoderms were described. 



Mastermann, 1903, describes the central ganglion over the sub- 

 neural blood sinus ; its position is as in Actinotrocha. This gives 

 off below a pair of large nerves each of which divides into six 

 branches for the six pairs of tentacle arms. Above it is prolonged 



•, ■■■■■ i fh- -N 



,.mm^- -.^..-....^ -'^^ipi 



Fig. 26. A. Cephalodiscus showing location of the nervous system aftei- 

 Hammer. B. Cephalodiscus after Masterman. C. Rhapdopleura 

 showing position of nervous system after Delage and Herouard. 



