130 



Mr. H. J. Carter on the 



Order V. ECHINONEMATA. 



Fig. 4. 



Fibre of Echinonemata : a, horny sheath of vertical or large fibre ; 

 b, core ; c, echinating spicules ; d d, horizontal or small fibre. 



Possessing a skeleton composed of horny fibre cored with 

 proper spicules internally and echinated with proper spicules 

 externally. Form of spicule chiefly acuate. 



Order VI. H0L0RHAPHID0TA. 



Fig. 5. 



Fibre of Holorhaphidota : a, vertical or large spiculo-fibre ; b i, hori- 

 zontal or small spiculo-fibre ; c, film of sarcode accompanying 

 spiculo-fibre. 



Possessing a skeleton whose fibre is almost entirely com- 

 posed of proper spicules bound together by a minimum of 

 sarcode. Form of spicule variable. 



