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-like swelling. 



cKt. 



FIG. 84. 



FIG. 85. 



FIGS. 84 and 85. A, Section through the anterior surface of the flabellum of an adult Limulus, showing four 

 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 liber, 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. 



