STRUCTURE OF THE RAYS. 



7 



determined not to be cheated out of a specimen in such a way a second time, I brought 

 with me a bucket of cold fresh water, to which article star-fishes have a great antipathy. 

 As I expected, a Luidia came up in the dredge, — a most gorgeous specimen. As it does 

 not generally break up before it is raised above the surface of the sea, cautiously and 

 anxiously I sunk my bucket to a level with the dredge's mouth, and proceeded in the 

 most gentle manner to introduce Luidia to the purer element. Whether the cold air was 

 too much for him, or the sight of the bucket too terrific, I know not ; but in a moment he 

 proceeded to dissolve his corporation, and at every mesh of the dredge his fragments were 

 seen escaping. In despair, I grasped at the largest, and brought up the extremity of 

 an arm, with its terminating eye, the spinous eyelid of which opened and closed with 

 something exceedingly like a wink of derision."^ 



Fig. 



The Goniasterida have pentagonal bodies, flattened on both sides ; the margin is 

 bounded by two rows of large marginal plates, larger than those on other parts of the disc, 

 and both entering into the formation of the border (figs. 7 c) ; their surface is variously 

 covered with granules, spines^ or pedicellarise, and they are often encircled by granules. 

 The upper surface of the disc and rays, within the marginal plates, is composed of 

 small, flat, hexagonal, pentagonal, or tetragonal ossicula 

 (fig. 8 A), and a like armature covers the under sur- 

 face ; the ambulacral avenues are bordered by a series 

 of square ossicula, which are often marked with parallel 

 grooves for lodging the spines (fig. 8 B). Towards 

 the extremities of the rays (fig. 7 d), the dorsal border- 

 plates are variously modified for lodging and protecting 

 the eyes. Fig. 7, after Miiller, represents Astrogonium 

 cuspidatum, M. and T., laid open from above to show, a, 

 the ambulacral plates ; b, the inner surface of the inter- ambulacral plates ; c, the upper 

 border-plate; and d, the terminal plate, modified to protect the eye. 



Fig. 8 shows the upper and under 

 surfaces of a small Astrogonium in 

 the British Museum Collection ; A 

 is the upper surface, exhibiting the 

 large superior border-plates, enclosing 

 the small polygonal discal plates with 

 their granular circles, which occupy 

 the whole intra-marginal upper sur- 

 face; B shows the base, with the 

 large inferior border-plates, and the 



Asirogonium cuspidatum, M. and T. 



Fig. 8 



1 Forbes, 'British Star- fishes,' p. 138. 



