PROCEEDINGS OF THE NATIONAL MUSEUM. 277 



The jaws are surrounded by a marginal group of long, slender, webbed 

 spines, of which there are about four or five on each side; the two inner- 

 most are somewhat the largest; on the actinal side of the jaws there 

 are also two much larger, isolated spines, one on ea(^h plate ; these are 

 entirely covered by a thick skin; when this is removed the spine is 

 flattened, tapered, and blunt at the tip, with a rough surface, but not 

 hyaline. 



The ambulacra! feet are large and in two regular rows. 



Color of the alcoholic specimen dull purple above, darkest on the 

 central part of the disk and interradial region ; beneath yellowish. 



Taken at station 2433, oft Newfoundland Bank, N. lat. 43° 05', W. 

 long. 50° 43', in 57 fathoms; one specimen (No. 12004, U. S. N. M.). 



This species not only differs from other known forms in having six 

 rays, but appears to be peculiar in the presence of naked interradial 

 grooves and genital slits. This last character may be sufficient to war- 

 rant its separation. as a distinct subgenus (Temnaster, Verrill), or even 

 as a genus. It differs from our other species also in having fewer and 

 stouter spines in the ventral combs; in the broader and flatter ventral 

 surface of the shorter rays; in the much thicker skin of the ventral 

 combs, and in the less evident comb of spines along the margins of the 

 rays. The dorsal membrane is also firmer and not at all granular; the 

 spinules over its surface are much more numerous, and the pores 

 between them are smaller and more numerous. 



The several young ones taken from the interradial slits all have six 

 rays, rendering it probable that this is the normal number, 



HYMENASTER MODESTUS, Verrill. 

 Hymenaster modestus, Verrill, Amer. Journ. Science, .\xix, p. 151, 1885. 



Body small, pentagonal, with concave borders, rays short, broad, 

 subacute. The dorsal membrane is thin, translucent, with minute 

 granule-like specks; the sj)iracular pores are few and minute; the dor- 

 sal cavity, beneath the membrane, is relatively large. Each adambu- 

 lacral plate bears three very slender, acute, rough spines; two are 

 placed obliquely at the inner edge, and of these the distal is usually 

 much shorter than the other; the third, which is external to the others, 

 but close to them, on the actinal side of the j>late, is more erect, longer, 

 and slightly larger; on the middle part of the rays there are often two 

 similar spines on the actinal side of the plate, close together. 



The actinal radial spines are very slender, not crowded, 10 to 18 on 

 each side; the longest ones are the fifth and sixth; these and those 

 beyond reach the margin, which is scalloped between them. The pores 

 between the inner ends of the actinal rays are round, and x>rotected by 

 an opercular spine or papilla, which is flat and expanded at the base, 

 but thin and slender at the tip. The dorsal pseudopaxill* are rather 

 large and few in number, with long terminal spinelets, which project 

 through the dorsal membrane as small spinelets ; they are pretty uni- 

 formly distributed, and there are no defined radial areas. 



