ax 



PHYLUM ECHINODERMATA 



357 



number of minute rounded tubercles, 

 of the ambulacra] 



neighbourhood 



FIG. 285. Anthenea, view of dorsal surface. 

 (After Sladen.) 



ossicles being beset with a 



which, in the immediate 



grooves, assume the char- 

 acter of short blunt 



spines. Here and there 



among the tubercles, 



usually one in the middle 



of each ossicle, are pv//- 



ccllaria', which differ 



widely from those of 



Asterias. 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- 



mdate is applied to pedicellarias of this description. In a living 



Anthenea many of the pedicellaria? 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. 2St>. Anthenea, view of ventral surface-. , i , 7 7 j 



(After siaden.) the inter-radial depression, 



