ECHlNODERMATA 81 



ten in number, expand to a disc not much larger than the 

 diameter of the body. The five grooves are visible as 

 lines along the sides. The skin is thickly covered with 

 calcareous plates of two forms one in that of elaborately 

 fretted shields, which are the " supporting plates " and on 

 each of these is a beautifully symmetrical little anchor 

 (Fig. 34). 



If a Synapta is taken with the hand it will be noticed 

 that it clings to the fingers, just like the familiar little 

 plant of our country lanes, the " goosegrass," (Gallium 

 aperina), and from like cause myriads of little hooks ; 

 only in Synapta the hooks are the points of the " flukes " 

 of the little anchors. 



In different species of Synapta the anchors differ a little 

 in detail. Thus in Synapta digitata the points are smooth, 

 while in a small species, abundant here (Synapta Galliennii), 

 the points are serrated. 



These spicules are favourite objects for the microscope, 

 and preparations of them, often arranged in the form of 

 rosettes (which is questionable taste, and not much com- 

 mended to the student), are sold at the optician's. 



An instructive and beautiful preparation of the skin of 

 Synapta, with the anchors each on its support, can be 

 easily made. 



The Synaptidse burrow in sand and in shell gravel, 

 whence they can be dug with fork or trowel. They live 

 near low-tide limit. 



I have not mentioned the beautiful Urchin Cidaris, in 

 which clubs take the place of spines, for I have never 

 known it found in the littoral zone, to which I am trying 

 to restrict myself, although I have, I fear, ventured once 

 or twice rather beyond it. 



