REPORT ON THE ECHINOIDEA—MORTENSEN 29 
Remarks.—The specimen is only 10 mm. in horizontal diameter, 
though evidently adult, having large genital pores covered by long 
genital papillae. Although in very poor condition this specimen, the 
only one found since the Siboga expedition, is of considerable impor- 
tance, affording proof that P. amphigymnum is not identical with the 
west American P. horridwm as maintained by Agassiz and Clark. It 
is, no doubt, closely related to that species but differs markedly from 
it in the almost total absence of plates on the periproct, in the struc- 
ture of the spines, and in the character of the ophicephalous pedicel- 
lariae. Also, it appears to reach only a much smaller size than the 
west American species. 
Genus ASPIDODIADEMA A. Agassiz 
ASPIDODIADEMA TONSUM A. Agassiz 
Aspidodiadema tonsum A. AGAssiz, Challenger Reports, Zoology, vol. 3, pt. 9, 
p. 66, pl. 8, figs. 1-9, 1881—nre Metsere, Siboga Echinoidea, p. 44, pl. 13, 
figs. 177-182, 1904.—MortTENSEN, The Danish Expedition to Siam 1899-1900, 
pt. 2, Echinoidea, p. 34, pl. 3, fig. 26; pl. 5, figs. 6, 31, 1904——A. Acassiz 
and H. L. CrarkK, Hawaiian and other Pacific Echini, Salenidae, ete., p. 98, 
pl. 50, figs. 3-5, 1908. 
Locality—Station 5348; Palawan passage; Point Tabonan bearing 
S. 89° E., 33.5 miles distant (lat. 10°57’45”’ N., long. 118°38’15’’ E.) ; 
685 meters; bottom temperature 13.56° C.; coral sand; December 27, 
1908. Twenty specimens. 
Remarks.—These specimens, ranging in size from 14 to 21 mm. in 
horizontal diameter, are all in rather poor condition and almost 
devoid of spines. In one of them, however, the basal 20 to 25 mm. of 
some of the aboral primary spines are preserved, enough to show 
that the spines of this species are curved as in other aspidodia- 
dematids. One of the specimens shows distinct traces of a purplish 
color. 
A specimen that was opened was found to contain only balls of 
mud, with Foraminifera and sponge spicules, in its intestinal canal. 
No ecto- or entoparasites were found with any of the specimens. 
Family MICROPYGIDAE 
Genus MICROPYGA A. Agassiz 
MICROPYGA TUBERCULATA A. Agassiz 
Micropyga tuberculata A. AGassiz, Challenger Reports, Zoology, vol. 3, pt. 9, 
p. 68, pl. 7, 1881.—pr MeEtsERE, Siboga Echinoidea, p. 59, pl. 14, fig. 215; 
pl. 15, figs. 216-231, 1904.—D6prrLeIn, Wiss. Ergebn. Tiefsee-Exped., vol. 5, 
Lief. 2, p. 169, pl. 21, fig. 4; pl. 42, figs. 1-6; pl. 43, figs. 1-18; pl. 44, fig. 1, 
1906.—H. L. CrarK, Catalogue of the recent sea-urchins in the British 
Museum, p. 48, 1925. 
