XU LIST OF ILLUSTKATIONS. 



FIGUEE • PAGE 



hy, hypoderm ; o, cuticle ; 6, anterior part of brain ; a, eye ; 



ne, nerve-fibrils ; u, anterior blood-vessel . . . • . . 1-^ 



16. Diagrammatic section through a papilla of touch of Onchidium. 



a', a", two layers of the cuticle ; a, biconvex thickened portion 

 of the cuticle ; 6, enlarged epithelial cells ; 6', ordinary epithe- 

 lial cells ; c, cellular body ; t?, cells ; n, nerve . . • • 1-^ 



17. Diagram of the structure of the soft and some of the hard parts 



in the tegmentum of a shell of a Chiton {Acanthopleura spiniger), 

 as seen in a section vertical to the surface, and with the margin 

 of the shell bordering on the girdle lying in the direction of 

 the left side of the drawing. /, Calcareous cornea; A, iris; 

 Qy lens ; k, pigmented capsule of eye ; n, optic nerve ; r, rods 

 of retina ; w', branches of the optic nerve, perforating the cap- 

 sule wall, and terminating in 6', 6', h\ ocular sense-organs ; 

 Pj P, nerves to sense-organ ; m, body of sense-organ cut across ; 

 a, p, fusiform body of sense-organ entire ; a, obconical termi- 

 nation of sense-organ ; c, nerve given off by one sense-organ 

 to another, 6" . . . . . . . . . . . . , . 15 



18. Diagram of forms of hairs in insects, a, Ordinary surface hair; 



6, plumose natatory hair ; c, hair of touch ; c?, auditory hair ; 



e, olfactory hair ; /, taste hair ; n, nerve hair . , . , 16 



19. Part of the proboscis of a fly (Musca). n, nerve ; g, ganglionic 



swellings ; s, tactile hairs or rods ; c, cuticle . . . . . . 17 



20. Right half of eighth segment of the body of the larva of a gnat 



{Corethra plumicornis), - ^(r, Ganglion ; iV, nerve ; ^, auditory 

 ganglion; gh^ auditory ligament; C'A, auditory rods; a, auditory 

 nerve ; e, attachment of auditory organ to the skin ; 6, attach- 

 ment of auditory ligament ; An., /(«', termination of skin-nerve ; 

 th, plumose tactile hair ; A, simple hair ; tg^ ganglion of tactile 

 hair; /m, longitudinal muscle ., ,, ,. .. ..18 



21. Taste-buds of the rabbit, X 4r)0 20 



22. a, Isolated taste-cells from the mouth of a rabbit; 6, two cover- 



cells and a taste-cell in their natural position, x 600 . . 20 



23. Termination of the nerves of taste in the frog, showing the 



ramifications of the nerve-fibjes and their connections with the 

 cells of taste, X 600 . . . . . . , . __ ^ . . 21 



24. Inner layer of skin of the proboscis o^ Asterope Candida^ x 400. 



a, Cuticle; 6, terminal (nerve) organs; c, ganglionic cells* 



d, longitudinal muscle; e, transverse muscle ,, ., ^ 22 



25. Taste-organ of the bee. B, Horny ridge ; R^ i?, sensory pits* 



0, C, skin of the mouth ; X, muscular fibres; A, Ay muscular 

 fibres ; S^ S\ a b c d e /, section of the skin of o?sophao-us . . 26 



