8 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
Locality —Station 5654; Gulf of Boni, Celebes; Cape Tabako bear- 
ing N. 17° E., 21.5 miles distant (lat. 3°42’00” S., long. 120°45’50” 
E.) ; 1,472 meters; December 18, 1909. Several specimens, most of 
them in poor condition. 
Remarks.—It is beyond doubt that Déderlein’s Phormosoma aden- 
cum is identical with P. verticillatum. This seemed almost certain 
from the description and figures given by Déderlein, the lacking of 
the characteristic verticillate aboral spines being the only tangible 
difference. A reexamination of the type specimen of P. adenicum, 
kindly lent me by the Berlin Museum, showed, however, that the 
verticillate spines are actually present, and the identity of adenicum 
with verticillatum is thus definitely proved. 
Parasite.—In the intestinal canal of this species was found a curious 
parasitic copepod, which has been described under the name Dichelina 
phormosomae by K. Stephensen.? The same species of parasite was 
found also in Phormosoma bursarium. 
Genus HEMIPHORMOSOMA Mortensen 
Hemiphormosoma Mortensen, Vid. Medd. Dansk Naturh. Foren., vol. 98, p. 162, 
1934: Monograph of the Echinoidea, vol. 2, p. 149, 1935. 
Characters.—This genus differs from Phormosoma in the very feeble 
development of the large areoles, which are confined to the two dis- 
talmost plates on the oral side, and the distalmost one on the aboral 
side. Also the fact that the demiplates of the ambulacra on the oral 
side are usually excluded from the edge of the ambulacral area is a 
noteworthy difference from Phormosoma. Whether the remarkably 
short valves of the tridentate pedicellariae represent a generic or 
merely a specific character cannot be decided so long as only a single 
species, the genotype, is known. 
HEMIPHORMOSOMA PAUCISPINUM Mortensen 
FIGuRE 1 
Hemiphormosoma paducispinum Mortensen, Vid. Medd. Dansk Naturh. Foren., 
vol. 98, p. 162, 1934; Monograph of the Echinoidea, vol. 2, p. 149, pl. 4, figs. 
1-3; pl. 74, figs. 16-18, 1935. 
Locality—Station 5359; Jolo (Sulu) Sea; (lat. 8°12’45’’ N., long. 
120°37’15’’ E.) ; 4,159 meters; January 9, 1909. Six specimens. 
Remarks.—A full description of this species has been given in my 
Monograph of the Echinoidea. It may only be pointed out that the 
gill slits are exceptionally well developed for an echinothurid (fig. 1). 
The very delicate structure of the test appears to stand in relation to 
the very great depth at which this echinothurid lives. In this feature 
it recalls another deep-sea echinothurid, Kamptosoma asterias (A. 
8 Vid. Medd. Dansk Naturh. Foren., vol. 93, p. 207, 19388. 
