I>KMIA\I. Stt'lliiiils (did h'l/iiiiif/s from llir Ki' rinadtc- 



U7 



also, in that species there are 2 rows of hiteral intermediate plates sepa- 

 rating the radials from the marginals, while the proportion r : R is different. 

 The arms are bhmtei'. and the adanibiilacral armature different. 



Asterina oliveri s]). iiov. Fig. 6. 



f>f this starfish. Avhich is very common in rock-pools, I have nine speci- 

 mens, all dried They have, unfortunately, been a good deal flattened, and 

 the spines rubbed off in places, but the general characters are readily seen 

 by comparison of one Avith another. 



Dimensions. — The largest is R 27, r 23, and from a series of measure- 

 ments it is found that /• : R is about 5:7. 



The outline varies from stellate to m-arly pentagonal, with only slight 

 incurvatures lietweeu the rays. Probably in life the centre of the disc is 



elevated, but it is now depressed. 

 The arms are, naturally, broad, and 

 end bluntly. The madreporite is 

 single, not prominent, much nearer 

 to the centre than to the margin, 

 its mesial edge being a little more 

 than half its own diameter from the 

 centre. 



The abactinal plates are cres- 

 centic, those along the middle of the 

 ray longer than elsewhere, so that 

 they are distinctly conspicuous. On 

 either side of this row the plates are 

 shorter, and this decrease continues 

 towards the middle of the inter- 

 brachial area. The spines are in 

 2 rows on each plate, closely set, 

 cylindrical, fine, and sufficiently 

 long to reach nearly to the neigh- 

 bouring plate when pressed down. 

 There are about 14 spines in each roAv on the mesial (radial) plates ; 

 about 10 on the curved interradials of the interbrachial area, but towards 

 the margin they get fewer, there being only some 5 or 6 on these smaller 

 plates. 



On the actinal surface each plate carries only 1 spine, shorter than those 

 of the abactinal plates, and a good deal stouter ; but on the 5 or 6 rows of 

 plates near the margin, Avhere they are reduced in size, each plate bears 2 

 spines. The colour of these actinal spines is greenish-blue, with white tip 

 and white base. 



The adambulacral armature : The furrow-spines are 2, cylindro-conical, 

 standing side by side in a row. Externally on the actinal face each plate 

 carries 1 spine, longer and stouter, blunt-pointed, and somewhat flattened. 

 The oral armature : Each interradial couple bears 10 spines {i.e., 5 

 on each side), arranged horizontally close together. Of these, i are long, 

 stout, flattened, and truncated, with 3 on either side rathe;- stouter. 



Each of the oral plates, at the angle, bears a single spine on its actinal 

 surface. 



Colour. — In life they are black, but in the dried state they are a uniform 

 dark bluish-grey. The lower surface is bluish-green, the spines here being 

 greenish, with white tips. 



Fig. (). — Aderinu olimri. 



A few of the radial.s and latero-tloivsals, 

 on some of whicli the double vows of 

 spines ai'e shown : one radial is wholly 

 exposed, but of the others only the 

 narrow spiniferous margin is visible {a). 



