174 Journal of Entomology and Zoology 



7. The close application of the deep strands to the superficial 

 gives the appearance of dorsal and ventral cells in the ganglia of 

 segmented animals. The suggestion of a dorsal sensory part and a 

 ventral motor has interest if not importance in this connection. 



8. A simple condition of relationship of nerve cells to each 

 other seems evident in the radial and circumoral strands of this 

 form as well as in starfish and these conditions may have an 

 important bearing in understanding the more complex relationships 

 of other species. If the conditions here simply shown are not 

 exactly reproduced in vertebrates or arthropods, they may give 

 some indication of the way in which the more complex have come 

 about. 



9. If the more superficial parts of the radial and oral system 

 are sensory and the smaller dorsal parts motor, then it seems that 

 the larger ventral strand must be a little more than sensory, as has 

 been shown by numerous experiments, because of its size and because 

 of its inter-relationships. In other words we have here the origin 

 of a central nervous system or associating part from a sensory por- 

 tion. This may be an important suggestion in connection with the 

 origin of the central nervous system in other forms. 



REFERENCES 

 Cuenot, L. 1887 



Etudes anatomiques et morphologiques sur les Ophiures. Arch. 

 Zool. Exper., Ser. 2, Vol. vi. 



Davy doff, C. 1901 



Beitrage zur kenntnis der Regenerationserscheinungen hei den 

 Ophiuren. Zeit. Wiss. Zool. Bd. lxix. 



Deluge et Herouard 1903 



Traite de Zoologie concrete. Ill Echinodermes. 



Hamann, O. 1889 



Anatomie und Histologic der Ophiuren und Crinoiden. Jen. Zeit. 

 f. Natur. Bd. xxiii. 

 Lange,W. 1876 



Beitrage zur Anatomie und Histologic der Asterien und Ophiuren. 

 Morph. Jahrb. Bd. ii. 

 Muller,J. 1854 



Ueber den Bau der Echinodermen. K. Akad. d. Wiss. Bd. xlv. 

 (Contribution from the Zoological Laboratory of Pomona College) 



