34 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
Genus EREMOPYGA A. Agassiz and H. L. Clark 
EREMOPYGA DENUDATA (de Meijere) 
Astropyga denudata DE MEDWERE, Siboga Echinoidea, p. 57, pl. 4, figs. 31, 32; pl. 
14, figs. 209-214, 1904. 
Hremopyga denudata A. AGAssiz and H. L. CiarK, Hawaiian and other Pacific 
Echini, Salenidae, ete., p. 122, 1908. 
Localities.—Station 5140; in the vicinity of Jolo (Sulu) ; Jolo Light 
bearing S. 33° W., 6.1 miles distant (lat. 6°08’45’’ N., long. 121°03’00’ 
K.), 189 meters; fine coral sand; February 14, 1908. One specimen. 
Station 5448; east coast of Luzon; San Miguel Point bearing N. 
23° E., 1.5 miles distant (lat. 138°23’10’’ N., long 123°45’19’’ E.); 86 
meters; June 4, 1909. Two specimens. 
Remarks.—Apart from some breakage of the test in the specimen 
from off Jolo these specimens are well preserved. The two from 
station 5448 are only half grown, about 45 mm. in horizontal diam- 
eter, but the genital pores are fully developed. 
The label of the specimen from station 5140 states: “General color 
dark claret, lines of brilliant purple on ambulacral [should be inter- 
ambulacral] area, 5 spots of same around periproct.” 
EREMOPYGA DEBILIS, new species 
Characters.—This new species differs very conspicuously from the 
only other species of the genus Z'remopyga known till now, F. denu- 
data, in the tubercles being very suddenly reduced in the proximal 
half of the oral side so as to produce an appearance much like that 
of Chaetodiadema. 'That the species does not, however, belong to 
Chaetodiadema appears very clearly from the character of the 
ambulacra, the tubefeet being well developed and the pores arranged 
in the usual arcs of three up to the edge of the peristome. Also the 
structure of the spines is as in 2’. denudata. 
The primary interambulacral tubercles are almost confined to the 
ambitus, there being only 5-7 tubercles in the outer adradial series. 
In the median area four series of large tubercles occur in the largest 
specimens, the two median series placed close together along the 
midline of the area. 
The whole aboral side is very naked. The blue spots in the naked 
bifurcating interambulacral area are small, isolated spots, or are 
united into a vertical line. The apical system has oculars IT and IIT, 
sometimes also ocular IV, exsert. 
The test appears to be of a much more delicate structure than that 
of E. denudata, and all the specimens are more or less crushed. But 
it is clear that the normal shape is in the main like that of £. denw- 
data, only it is not sunken at the peristomial edge or apically, and 
the ambulacra are not raised on the aboral side. 
