Pomona College, Clarcmont. California 55 



The chief radial nerves, as is well known, are concentrated 

 into ganglion-like swellings at the intervals between the vertebrae 

 and here from the dorsal nerve cord strands are sent into the mus- 

 cles of the arms. 



Fig. 31. Nervous system of Sehpent-Stars. A. Diagram of the nervous 

 system of a serpent-star, a part of the disc and the bases of three 

 rays shown. In the upper right end ray the superficial nerve ring 

 and radial nerve are removed to show the deeper nerves. In the 

 others and on the disc other nerves are shown. On the disc the 

 superficial nerve-net is given. Out from the radial and circum-oral 

 nerve the chief branches to the tube feet, etc., are shown. B. Dia- 

 gram of the nervous system of one of the arms cut across showing 

 large cavity of an arm in deep shading and the lowest cavity 

 within radial nerve, with branches to spines and tube-feet. C. 

 Diagram of section of an arm after Hamann. D. Through the arm 

 at another level. E. Section through radial nei've. Hamann. F. 

 Section through sense papilla. Hamann. 



