Introduction to Animal Morphology. 79 



flagellate nuclei of modified endodermal (?) cells. The forms 

 included herein are singularly plastic, easily modified by ex- 

 ternal conditions. The group with inconstant, simple, 

 tlermal pores constitutes the sub-order Ascones.* The series 

 with tortuous branched canals in the wall of the gastraeal 

 cavity are named Leucones, while those with regular, straight, 

 unbranched vessels and budding tubes are Sycones ; any of 

 these may possess either simple or three- or four-rayed 

 spicules, or two or more kinds together, and by these Haeckel 

 divides them into genera. The flagellate plastides of 

 Leucosolenia (Ascones) have been regarded by James-Clark 

 ^as separate organisms grouped in a colony (see Synura). 



CHAPTER XII. 



' SUB-KINGDOM 3. CCELEXTERATAf (Lcuckarf). 



AQUATIC radiated personse (often in colonies) of more 

 than two antimeres, having a body cavity opening at 

 -one pole by a mouth often surrounded by feelers 

 (tentacles). The body consists of two membranes, an 

 inner, cellular or endoderm, which at the mouth joins 

 the outer, or ectoderm. In the colonial forms, the 

 tubular prolongation of the body^ cavity of each 



<na communicates with that of its neighbours in 

 mmnn stem of the colony (Ccenosarc), allowing 



iimunity of nutrition, and tin* fluid, produced by 



in tli' stomach of each, circulates in this 



tubul m, movi-.l by tin* lining cilia. I )ii- 



J'-n-miat;< cli-nn form support-, loco- 



These arc tin- 



t Dijilol)! t with tin- Al> lactic-. i 



(I'roto/.u), an-! I :xlu<Iin- all the < -oa. 



