REPORT ON THE ECHINOIDEA—MORTENSEN 21 
involute form of tridentate pedicellariae (pl. 1, figs. 2, 3) so closely 
resembling that of A. coriaceum that one might be inclined to think 
this specimen rather to be referable to the latter species. As a mat- 
ter of fact, I believe this specimen to be a hybrid between A. coriacewm 
and A. owstoni var. nudum. Since the two forms evidently occur in 
the same area (the China Sea) there is so far nothing to prevent them 
from forming hybrids. The unfortunate fact that there are no 
dactylous pedicellariae to be found in the specimen under considera- 
tion prevents reaching a definite conclusion. The dactylous pedicel- 
lariae of A. owstoni and A. coriaceum are very different—3-valved 
and of a very primitive type in the former, 5-valved and of a highly 
finished type in the latter. 
Genus HAPALOSOMA Mortensen 
HAPALOSOMA PELLUCIDUM (A. Agassiz) 
Asthenosoma pellucidum A, AGAssiz, Challenger Reports, Zoology, vol. 3, pt. 9, 
Echinoidea, p. 85, pl. 18, figs. 1-6; pl. 18a, figs. 14-17; pl. 19, figs. 1-6, 1881. 
Hapalosoma pellucidum Mortensen, Ingolf Echinoidea, pt. 1, pp. 55, 64, pl. 11, 
fiz, 19; pl. 12; figs. 8-10, 14: pl. 13, figs:.20, 24, 25, 1903; pt. 2, p: 21, 1907; 
Monograph of the Echinoidea, vol. 2, p. 271, pl. 58, figs. 1-11; pl. 54, figs. 1, 2; 
pl. 83, figs. 1, 2, 4-10, 14, 16, 18, 1935. 
Araeosoma pellucidum A. AGASsIz and H. L. CLarK, Hawaiian and other Pacific 
Hechini, Echinothuridae, 1909, p. 181. 
Locality. —Station 5135; in the vicinity of Jolo (Sulu) ; Jolo Light 
bearing S. 46° W., 11.9 miles distant (lat. 6°11'50’" N., long. 
121°08’20” E.) ; 294 meters; bottom temperature 14.11° C.; fine coral 
sand; February 7, 1908. Two specimens. 
Remarks.—There can be no doubt that this beautiful and, because 
of its banded spines and its pedicellariae, easily recognizable species 
is closely related to the forms in the genus Avaeosoma, representing a 
special branch of that genus, as evidenced by its remarkably trans- 
formed dactylous pedicellariae. Still, I cannot agree with Agassiz 
and Clark in simply referring it to Araeosoma. Nothing at all is 
gained by referring it to the large genus Araeosoma, within which, 
together with another species from the Japanese seas hitherto incor- 
rectly identified with H. peiluctdum, it must form a group of its own. 
I shall, therefore, have to maintain the genus Hapalosoma. 
Genus ASTHENOSOMA Grube 
ASTHENOSOMA VARIUM Grube 
Asthenosoma varium GRuBE, Jahrb. schles. Ges. vaterl. Cultur, vol. 45, p. 42, 
1868.—MorTENSEN, Monograph of the Echinoidea, vol. 2, p. 280, pls. 55-58; 
pl. 61, figs. 1-6; pl. 62, figs. 1, 2; pl. 82, figs. 1-8, 5, 6, 9-14, 1935. 
Asthenosoma grubei A. AGASSIz, Challenger Reports, Zoology, vol. 3, pt. 9, 
Echinoidea, p. 82, pls. 15-17, 1881. 
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