APPENDIX. 215 



species. It is perfectly free, and so simple in its 

 structure, that when the sac which forms its body is 

 turned inside out it will continue to perform the 

 functions of life as before. The greater part, however, 

 of these Hydraform Polypes, although equally simple 

 as individuals, are connected in a compound life by 

 means of their variously formed polypidom, as the 

 branched system of cells is termed. The Hydroid 

 Zoophytes are represented in the first plate by the 

 following examples. 



HyDPvOIDA. 



Seetulaeia EOSEA. PL I. jig. 6. 



A species which has the cells in pairs on opposite 

 sides of the central tube, with the openings turned 

 outwards. In the more enlarged figure is seen a 

 septum across the inner part of each cell which forms 

 the base upon which the pol}^e rests. Fig. 7 h 

 indicates the natural size of the piece of branch re- 

 presented; but it must be remembered that this is 

 only a small portion of the bushy shrub. 



