OF ZOOPHYTA 293 



their free ends; the mouth (m) en- 

 circled by an aquiferous channel, 

 with which the cavities of the ten- 

 tacles are in open communication, 

 and from which five longitudinal 

 canals (aq 2 , aq 2 , aq*, aq~) extend back- a 

 wards, just beneath the skin, to the 

 posterior end of the body ; the suck- 

 er-like feet, (s 2 ,) which have been in- 

 creased in number to four, protruded 



from the body through the apertures Fig. 193. 



which lie in pairs close to the inferior mid-line, and their in- 

 terior in direct communication with the middle longitudinal 

 canal by means of a narrow tube (s l ) which passes from each 

 of them to the latter ; the madreporic canal (me) in the dis- 

 tance, at the dorsal mid-line, and swollen at the end ; the poste- 

 rior end of the intestine expanded transversely into a broad 

 sac (if 3 ), which eventually becomes the double respiratory organ ; 

 five longitudinal muscular bands corresponding in position with 

 the longitudinal canals (aq 2 , &c.) ; and finally a few transverse 

 .or annular muscular bands (bd) lying exterior to the longitu- 

 dinal ones, and which eventually broaden so as to touch each 

 other, thus forming a continuous contractile sheath immediately 

 beneath the skin. 



What is the process of development from this period onward 

 to the adult state was not ascertained by the investigators, 

 Messrs. Koren and Danielssen ; nor is it necessary for our pur- 

 pose that we should know, since we have followed it far enough 



Fig. 193. The same as figs. 191, 192, but a little more than a month older 

 than the last. Natural size about 1 of an inch long. A view from below, m, the 

 mouth ; /J the rudiments of the calcareous buccal ring ; <, <i, the feelers; s, s 3 , 

 s 4 , s 5 , the adhesive disc of the sucker-like reptatory organs ; me, the madreporic 

 canal ; aq, a saccular appendage of the aquiferous ring about the mouth ; o-, 

 aq' 2 , fl^ 4 , aq 7 , the longitudinal aquiferous canals, seen as it were through the lon- 

 gitudinal muscular bands which underlie them ; s 1 , the canals which lead from 

 a<? 4 to the interior of the sucker-like feet (s 3 ) ; bd, the transverse annular 

 muscular bands; </ 3 , the incipient respiratory branches. From Koren and 

 Donielssen. 



