OSJ 



wl 

 gn 



Kt 

 i 

 D 



PHYLUM ECHINODERMATA 



357 



number of minute rounded tubercles, 

 neighbourhood of the ambulacra] 



cell 



t 



ossicles being beset with a 



which, in the immediate 



grooves, assume the char- 

 ter of short blunt 

 ines. Here and there 

 mong the tubercles, 



usually one in the middle 



of each ossicle, are pedi- 

 II aria', which differ 

 idely from those of 

 .sterias. Each pedicel- 



laria in Anthenea is a 



small, narrow-oblong, cal- 

 careous body, consisting 



of two parallel narrow 



valves or jaws : these, in- 

 stead of being supported 



on a flexible stalk, are 



articulated with the edges 



of a slit-like depression 



on the surface of the flat 



ossicle, and are thus on 



a level with the general 



surface. The term val- 



mdatc is applied to pedicellariae of this description. In a living 



Anthenea many of the pedicellariaB will be found to have their values 



widely open; when they 

 are touched the valves 

 close together, gradually 

 opening again after a little 

 time. The ambulacral 

 spines bounding the am- 

 bulacral groove are flat- 

 tened and blunt, and 

 arranged in fan-like fasci- 

 culi. Round the border 

 separating the dorsal and 

 ventral surfaces the plates 

 are arranged in two some- 

 what irregular rows. 



The dorsal surface is 

 strongly convex, but not 

 uniformly so, there being 

 a more or less distinct 

 depression in the form of 



a shallow open groove, 

 FIG. 286. Anthenea. view of ventral surface. ,-, , -j j 7 ' 



(After siaden.) the inter-radial depression, 



FIG. 285. Anthenea, view of dorsal surface. 

 (After Siaden.) 



