ECHINOBEEMATA. 137 



plates are curved ; the plates themselves are at first broader than 

 long, bnt during their gradual diminution in size they have at one 

 time their aboral edge equal to their longitudinal axis ; stiU further 

 out they are longer than broad. About six, short, poorly developed 

 spines are, found on each of the side arm-plates near the disk, of 

 which the largest are median in position ; they diminish in number 

 and size as they approach the free end of the arm. Two small ten- 

 tacle-scales. 



Upper surface (in alcohol) dark yellow, with spots or patches of 

 brown ; the whole of the actinal surface pale flesh-colour. Although, 

 as a rule, three consecutive segments are coloured by a darker trans- 

 verse patch, there may be only two, or there may be four so orna- 

 mented, and, as irregularities, one or more than four ; but the colo- 

 ration always extends on to the sides of the arm, though it never 

 passes on to the lower surface. Or the whole may be very many 

 shades darker, and then the darkest parts are not especially remark- 

 able ; this last mode of coloration appears to be by far the most 

 common. 



Port MoUe, Queensland, 14 fms., rock ; and Port Denison, 

 3-4 fms. 



In some examples, which are very much smaller, from Torres Straits 

 the radial shields are oviform, the upper arm-plates are not nearly 

 so wide nor so distinctly carinated ; the central rosette may be only 

 barely indicated, though the central plate is very distinct ; the plates 

 of the interradial series have no small marginal secondary plates. 

 The side arm-plates at the base of the arm are proportionately much 

 larger, and in consequence diminish the breadth of the lower as well 

 as of the upper arm-plates. Striking as is the difference in effect 

 produced by these differences in character, they are, I think, only 

 to be ascribed to age. 



5. OpMopeza conjimgens. 



This species seems to strengthen the opinion, more than once ex- 

 pressed by Mr. Lyman, that the genera Ophiofpeza and Peetinura are 

 barely to be distinguished. Without a divided mouth-shield, it has 

 the arms not rounded, as in 0. fallax, but keeled above, as is so often 

 the case in Pectinwra. 



Most closely allied to 0. fallax, it may be distinguished by the 

 somewhat coarser granulation of its disk, the smaller number of 

 mouth-papillse, and the broadened upper arm-plates. 



Disk pentagonal, flattened, 17'5 millim. diam. in one example, 

 completely covered by a delicate and regular granulation (of about 

 twenty graniiles to 1 millim.), the underlying scales not large ; the 

 radial shields, in perfect specimens, only indicated by depressions. 

 Mouth-shields not divided, wider than long, with a wide convex 

 adoral edge, straighter sides, and a barely convex aboral margin. 

 Side mouth-shields small ; the space between the mouth-shield and 

 the edge of the jaws is marked by a granulation, much coarser than 

 that which obtains elsewhere on the disk. Mouth-papillsB seven. 



