406 PBOE F. JEFEBEY BELL, OX THE [May 1, 



to me to be fully justified in regarding Asterias volsellata as a sign 

 that the difference between the Asteriidae and Brisingidae is not so 

 great as has been generally supposed. If I do not accept his view 

 of the origin of the latter family, it is only because my capacities 

 are not sufficient for me to be able to understand how it has been 

 possible for " complete isolation " to have had an ' : action " on them. 

 On this point I, and I believe many others, would be glad of a 

 more detailed explanation. 



The " type " is said to have come from 95 Ems., and Mr. Bassett- 

 Sinith's example from 45 fins. 



IV. OPHIUROIDEA. 



Pectixuba sphenisci, sp. nov. (Plate XXV. figs. 7-9.) 



This species stands with P. spiaosa, P. arenosa, P. infernalis, and 

 P. her os. of Mr. Lyman's arrangement, and P. capensis, Bell ; for 

 it has the disc covered under its granulation with coarse scales 

 (much coarser than in /*. caj^ensis), and there are no pores between 

 the under arm-plates. There are five or six short arm-spines and 

 two tentacle-scales. 



Radial shields not constant, but the typical arrangement pro- 

 bably is that they are small, naked, triangular, and separated from 

 one another by a third triangular plate. The granulation of the 

 disc is coarse, and the peripheral plates large. The arms are not 

 wider at their base than at some distance outside the disc, nor 

 carinated; accessory mouth-shields moderate in size, irregularly 

 oval or quadrate. Six quite short arin-spines ; fourteen mouth- 

 papilla?. As often is the case the outermost is by far the smallest, 

 and the penultimate distinctly the largest of the series. Mouth- 

 shields almost triangular ; granulated space between mouth- 

 papillae and shield well-marked. 



The side arm-plates encroach on both the upper and lower 

 surfaces ; the upper arm-plates are wider distally than proximally, 

 and the lower are irregularly hexagonal. 



Ground-colour, when drying, greyish, with brown patches on 

 disc and regular bands of brown extending over three or four 

 joints on upper surface ; lower surface uniformly pale. 



Diam. of disc 5*5 mm. ; length of arm about 40 mm. 



Holothuria Bank, 15 fms. 



Pectiiotba elegans, sp. nov. 



This species belongs to Mr. Lyman's second division ; but 

 differs from all in having no pores between the under arm-plates. 

 There are six rather short, moderately stout arm-spines and two 

 tentacle-scales. 



Radial shields naked, quite distinct, moderate in size, darker 

 than the rest of the test ; granulation rather fine, similar over the 

 whole of the dorsal surface of the disc. The arms taper very 

 gradually from their base ; accessory mouth-plates small, semi- 



