114 



GENERAL AND SPECIAL CUTANEOUS SENSE ORGANS. 



groups that are surrounded by an ill defined sheath and supplied by a single 

 nerve. (Fig. 84.) 



The slender outer ends of the sensory cells unite to form a dense, conical 

 body, enclosed in a bulb-like enlargement at the base of a chitenous tubule. 

 Before uniting, the cell ends become especially distinct and each one develops a 

 minute, bead-Hke swelling. 



Fio. 84 



Figs. 84 and 85. — A, Section through the anterior surface of the flabellum of an adult Limulus, showing fovir 

 flabellar sense organs — von Rath's preparation; B, section throngh one of the gill warts of an adult Limulus, show- 

 ing the peculiar bell-shaped terminal " hairs" and the associated cluster of sensory cells and chitenous tubules — ^von 

 Rath's preparation; C, terminal hair of a gill wart, more highly magnified; D, diagram of a slime bud, Limulus; E, 

 taste bud from the pharynx of an embryo Catastomus {after Johnston) ; F, a taste organ from the skin of an 

 adult Lampetra (ajter Johnston); G, a neuromast from the skin of Catastomus (after Johnston) ; H, diagram of an 

 arachnid sense bud. 



The apex of the cone extends outward as an exceedingly minute fiber, through 

 a small chitenous tubule, probably as far as the outer surface of the flabellum. 

 Between the slender necks of the organs are a few elongated cells, and similar 

 ones, but smaller, are seen in the canals through which the chitenous tubules 

 pass to the exterior. 



