ECHIKODEEMATA. 511 



3 A'-, which seems to be new to science, but of which more mature 



specimens must be obtained before tho species can bo named and 

 described. 



From the He des Roches, which is on a separate coral-bank from 

 the other islands, came : — 



Phyllacanthus baculosus (13 fms.). 



At Providence Island, which is 240 miles S."W. by S. of the 

 Amirante group, the only Echinoderm obtained was 



Ophiothrix propinrpia. 



This species seems to be somewhat variable in the details of its 

 coloration ; originally described by Lyman as having a blue mark- 

 ing, some specimens collected by the ' Challenger ' were reported by 

 that eminent authority as " red varieties." Such are most of the 

 specimens in the present collection. 



From Glorioso Islands come : — 



Ophiocoma scolopendrina and Ilolothuria pardalis. 



In addition to tho more or less well-known species of Ophiurids 

 the names of which have just been given, the collection contains 

 examples of some very remarkable forms which, so far as I am able 

 to tell, have not yet received description at the hands of any 

 naturalist. 



In one case I feel justified in establishing a new genus, for 

 which, as the term Hemi^lax is already in use, I propose that of 

 Neoplax. 



NEOPLAX. 



Disk covered with a rather thick skin, not richly granulated. No 

 radial shields ; the dorsal arm-plates present, but incompletely 

 developed and not touching one another. Arms long, slender, 

 coiled on themselves, but not divided. A few mouth-papillae and a 

 few teeth, but no fringe of spines to either. A moderate number of 

 short arm-spines, with their basal portions embedded in tho skin. 

 The tentacle-scale single and very small. The genital slits long 

 and the scale large. 



This interesting genus appears to belong to Mr. Lyman's third 

 group of Ophiurida?, or the Astrophyton-like Ophiurans. Notwith- 

 standing the absence of radial shields, it does not seem to have any 

 special affinity to Ophiomyces ; but, on the whole, to stand not verv 

 far from Ophiomyra, from which, however, it is to be distinguished 

 (1) by the complete absence of radial shields, (2) the great reduction 

 of the plates at the margin of the disk, (3) the twisted arms, and 

 (4) the absence of the modified spines on the oral processes. 



