CHAPTEE VI 



EXTERNAL CHARACTERS OF CYCLOSTOMATA AND OF FISHES 



EXTERNAL CHARACTERS COLORATION POISON GLANDS AND 



POISON SPINES PHOSPHORESCENT ORGANS. 



In all the Cyclostomata the body is Eel-like in shape, the head 

 and trunk being nearly cylindrical, and the tail somewhat flat- 

 tened from side to side. In Petrnmyzon the head terminates in a 



hr.cl.i 



pn. 



Fig. m.—Petromyzo7i mannus. A, ventral ; B, lateral ; and C, dorsal, view of the head 

 hr.d.l, First branchial cleft ; iuc. f, buccal funnel ; eye, the eye ; mth, mouth ; na.a-p, 

 nasal aperture ; p, papillae ; pn, pineal area ; t^, f; e, teeth of buccal funnel ; t\ 

 teeth on the tongue. (From Parker and Haswell, after "W. K. Parker.) 



ventrally-directed, funnel-like cavity — the buccal funnel — in the 

 roof of which the relatively small mouth is situated (Fig. 91, A.). 

 The m-argin of the funnel is fringed by a series of short papillae, 



ISO 



