174 LECTURE IX. 



side. Chyle, or reduced cliymous particles of the food, with sea-water, 

 circulates freely through the cavity and canals of the system above- 

 described, and effete particles are sent out with the fluid by the 

 excretory pores, which are homologous with those of the correspond- 

 ing system of canals in the Ci/ancea {Jig. 76. c, c), and only remotely 

 analogous to the anal outlet of the true intestinal canal in the Bryozoa 

 and higher forms of animals. In Cytaeis, Geryonia^ and Thau- 

 mantias four canals are continued from the digestive chylaqueous 

 cavity to the marginal circular canal ; whilst in jEquorea not fewer 

 than seventy-four canals radiate from the stomach to the marginal 

 canal. 



Asassiz has described the longitudinal muscular fasciculi beneath 

 the superficial rov/s of vibratile fringes, and the pinnate bundles of 

 fibres attached to the sides of those rows, and which penetrate into 

 the substance of the gelatinous mass. By means of these muscles, 

 the fringes, although they usually move together, yet sometimes act 

 independently, and even particular cilia in each lamelliform fringe 

 may move whilst the others are at rest. The same acute and inde- 

 fatigable observer has figured the radiating fibres of the muscles 



o o o 



which dilate the mouth, and the circular fibres which close it, and 

 the diverging fibres of the main vertical fasciculi, which form a kind 

 of sphincter around the tube leading into the tentacular sheath.* 



The evidence of the nervous system in the Ciliogrades is doubtful 

 and conflicting. 



Dr. Grant f has described and figured a double filamentous chord 

 connecting a chain of eight ganglions around that extremity of the 

 Bero'e ( Cydippe) p'deus {Jig. 77, b), from near which the two long 

 cirrigerous tentacula {d d) are protruded, and where he supposed the 

 mouth to be placed. "Whatever analogy such nervous system may 

 bear to that of the Echinoderms in the circular disposition of the 

 central filaments, and the radiation of nerves from that centre, it has 

 none in regard to its situation, for the mouth of the Beroe is at the 

 opposite end of the body. | 



Milne Edwards § and Will || both reject the above described 

 nervous system. A single cysticle appears to be present in all 

 Beroida; at the anal pole of the body, in a depression, protected by 

 lobes of the integument ; and beneath the cysticle is a yellowish 

 mass of a ganglionic appearance, which both the above-cited ob- 

 servers refer to the nervous system. The cysticle contains some 

 clear fluid with an aggregate of crystalline corpuscles of a white 



* CXLVIII. PP..332— 339. pi. 2. n, o, p. f CXLIX. p. 10. pi. 2. f. 1. 



X CXLVII. p. 20G. pi. 4. § CXLVI. p. 207. || CXIV. p. 44. 



