REPORT ON THE ECHINOIDEA—MORTENSEN 11 
region of this species, hitherto known only from the North Pacific 
(Japan to the Aleutian Islands) has thus been established. This dis- 
tribution is in full accord with that of so many other deep-sea echino- 
derms that it might well have been expected in advance. 
The name “’chinosoma hitherto used for this and other species is 
preoccupied no less than three times—for a holothurian, a beetle, and 
an earwig. The name 7'romikosoma, proposed by me in 1903° for 
the species koehleri, which is undoubtedly congeneric with the pres- 
ent species, as is justly maintained by Agassiz and Clark, thus takes 
the place of Hchinosoma as the name of the genus to which this 
species should be referred. Regarding the characters of this genus, 
in a restricted sense (Agassiz and Clark took it in a wide sense 
comprising also the genus Hygrosoma, which is entirely untenable), 
I must refer to my Monograph of the Echinoidea, vol. 2, p. 164. 
Genus SPERGSOMA Koehler 
SPEROSOMA CRASSISPINUM Mortensen 
FIGURE 2 
Sperosoma crassispinum MortTENSEN, Vid. Medd. Dansk Naturh. Foren., vol. 98, 
p. 163, 1984; Monograph of the Echinoidea, vol. 2, p. 195, pl. 9, fig. 2; 
pl. 10, fig. 2; pl. 77, figs. 18-17, 1935. 
Locality.—Station 5616; Molucca passage; Tifore Island (C.) 
bearing N. 40° W. 35 miles distant (lat. 0°3230’’ N., long. 126°31’30’ 
H..) ; 1,866 meters; gravel; November 22, 1909. One specimen. 
Figur 2.—Spicules from tubefeet of Sperosoma crassispinum Mortensen: a, From oral 
tubefoot; 6, from aboral tubefoot. X 200. 
Remarks.—A. full description and figures of this specimen are 
given in my Monograph, to which the reader is referred. It has 
a size of about 145 mm. in diameter. 
Besides by the rather coarse spines—a feature to which the specific 
name refers—this species differs markedly from the other known 
5 Mortensen, Ingolf Echinoidea, pt. 1, p. 62, 1903. 
