44 



Journal of Entomology and Zoology 



the eye-spots. Between and surrounding the visual cells are 

 numerous bipolar, elongate supportive cells which stain strongly 

 with connective tissue stains. In some cases the eye areas are 

 not in the form of follicles as Pfeifer, 1901, has shown in a species 

 of Astropectcn. In those eye areas which appear as follicles a 

 lens has been described and figured by Pfeffer and others but I am 

 inclined to the interpretation of Cuenot, 1887, who believed that 

 no lens is present. In fact, in some sections which I have seen 

 there was no sign of even a membrane over the mouth of the 

 follicles. 



In the superficial system many long supportive cells help to 

 make up the bulk of the nerve cord. These stain deeply with 

 usual stains and at their inner ends are more or less intertwined. 



Fig. 27. A. Diagram of a Starfish cut so as to expose internal as well as 

 external parts of the nervous system. In the center the deep nerve 

 ring is shown by a dark cui'ved line, the surface nerve ring by 

 a thicker line. These parts are continued into the arm cut longi- 

 tudinally on the right. Nerves to the tube-feet are shown. The 

 superficial nerve plexus and internal nerves are indicated. B. 

 Cross section of the radial nerve of starfish, superficial and deep 

 parts shown. C. Nerve cells and supportive cells from the central 

 nervous system. D. Section through one of the pedicellariae of sea- 

 urchin showing distribution of nerves, after Ilamann. E. Section 

 through "taste knob" of sea-urchin. Hamann. 



