183 



ZOOLOGY. 



The month is situated on a disk (fophophore, Fig. 127, B), 

 bearing the tentacles, which are hollow processes of the 

 body-walls, communicating Avith the body-cavity, the blood 

 flowing into them, there being aerated, while they are exter- 

 nally ciliated. They serve both to catch food and for respir- 

 ation as makeshift gills. Hyatt states that the tentacles are 

 used not only to catch the prey, but for a multitude of other 



offices. They are each capable of in- 

 dependent motion, and may be twisted 

 or turned in any direction ; bending 

 inwards, they take up and discard 

 objectionable matter, or push down 

 into the stomach and clear the 

 oesophagus of food too small to be- 

 acted upon by the parietal muscles. 

 They are also employed offensively in 

 striking an intrusive neighbor, and. 

 their tactile power, sensitive to the 

 slightest unusual vibration in the 

 water, warns the polypide of the ap- 

 proach of danger. 



The digestive canal hangs free in 

 the body-cavity, only attached by the 

 mouth and anus to the walls of the 

 body. It consists of a pharynx, a 

 large stomach, and an intestine which 

 lie * b J the sidc of the Pharynx, since 



ivmateitafrw- 



the canal lua a .rrnple deep dorsal 



ticosn. t>r, tentacular branchiae 



ofiophophore ; a, oesophagus ; flexure, the vc"t being situated on 



v, stomach ; r, intest ne ; a, 



anus ; i, cell ; x, posterior, . >, 



anterior cord, at the insertion 



of which into the body the mOUtll. 



generative products are (revel- , , / / 7 \ , 



oped: (, testes ; o, ovary ; m, by a sort ot ligament (juniculus) to 



retractor muscles of the auto- v^'nt nn fl lp hftflv.wfllls np-ir tVi<x 

 rior portion ol 1 the cell ; inr, a POITITJ Oil 1116 DOQy-WailS, 1 



mi " de -~ 



.lie dorsal or cardiac side, near the 

 Usually the stomach is tied 



mouth. The nervous system is rep- 

 resented by a double ganglion form- 



ing a single mass situated between the mouth and vent ; it 

 is highly contractile and changeable in form. There is na 

 heart and no circulatory apparatus. The sexes are united 

 in a single polypide, the glands forming masses growing on 



