﻿182 ASTROPIIYTON EUCNEMIS. 



Description of a Specimen. — Diameter of disk, ST""' ; from outer 

 side of madreporic shield to outer corner of opposite mouth-slit, 23"°'- ; 

 breadth of arm inside the first fork, 20""". Distances from each fork to 

 the next beyond : — 



First fork to second, jgmm. 



Second " " third, 17 " 



Third " " fourth, 23 " 



Fourth " •' fifth, 32 " 



Fifth " " sixth, 28 " 



Sixth " " seventh, 30 " 



Seventh " " eighth, 27 " 



Eighth " •' ninth, 17 " 



Ninth " " tenth 17 " 



Tenth " " eleventh, 15 " 



Eleventh " " twelfth, 15 " 



Twelfth " " thirteenth, . . . . 17 " 



Thirteenth " " fourteenth, .... 9 " 



Fourteenth " " fifteenth, 13 " 



Fifteenth " " end, 1 " 



280"™" 



Distance from outer side of madreporic shield to inner points of tooth- 

 j^apillfe, to that between outer corners of mouth-shts, 15:8. Mouth- 

 papillae, tooth-papilla?, and teeth, about twenty in all ; sharp, rather 

 slender, spine-like ; the longest 2.5 long ; those near the outer corners 

 of the mouth-slits smaller. Madreporic shields three (there is com- 

 monly but one), like irregular, raised scars, broader than long, often 

 broken. Under sides of arms covered with microscopic granulation, 

 which looks smooth to the naked eye. Upper surface and sides of 

 arms covered with distinct grains, which are pretty closely set on the 

 upper surface, but more scattered on the sides ; on the fine terminal 

 branches they appear as a regular double row of large, prominent grains, 

 each grain bearmg a little hook ; the tendency to arrange themselves 

 in vertical rows may be noticed even at the base of the arm. Inter- 

 brachial spaces of disk above, and brachial spaces between the radial 

 ribs, covered with scattered grains ; in the centre of the disk, grains 

 closer and rather larger ; round the margin of the disk a sort of belt 

 of close-set grains ; interbrachial spaces below apparently naked, but 

 really covered with microscopic grains. Radial ribs moderately raised, 

 rounded, and without sharp edges, reaching not quite to the centre ; 

 length to breadth, 43 : 9 ; pretty closely covered with fine grains, 

 which are about the size of those on the arms, and are more numerous 

 along the margins of the ribs ; on the outer end, grains larger, and 

 ahuost like small, blunt spines ; just over the arm the end of the rib is 

 naked. Tentacle-scales spiniform, much hke the teeth in shape and 

 size ; within the disk only two or three to each pore, and on the one or 



