REPORT OF THE ECHINOIDEA—MORTENSEN 119 
of the petals which are thus occluded. The labrum is straight cut 
at the anterior end, whereas in Airsutus it is quite prominent. The 
periproct is marginal, in hirsutus inframarginal. 
The specimens are all large and high, but somewhat different in 
outline, as appears from the following measurements of two speci- 
mens: (1) 180 mm. long, 123 mm. broad, 75 mm. high; (2) 115 mm. 
long, 115 mm. broad, 81 mm. high. 
One of the specimens (all of them dry) has the spines fairly well 
preserved. ‘They are quite short, as in P. hirsutus. The pedicellariae 
are as in hirsutus, but in the present species also rostrate pedicellariae 
are found, even in great numbers, this type of pedicellariae being 
unknown in hérsutus. 
The characters pointed out above leave no doubt that the specimens 
collected by the Albatross are specifically different from those collected 
by the Siboga. One would have expected them to be identical with 
the single specimen of Plestozonus hitherto known (from the Flores 
Sea) ; but this is evidently not the case, to judge from the description 
and figures given by de Meijere, the correctness of which it is hardly 
permissible to doubt. It is particularly to be emphasized that all 
the specimens agree in the important character of the petals that the 
last 1-3 plates are occluded. 
The specimens from station 5242 were all very badly crushed, but 
it has been possible to fit the fragments together so as to form toler- 
ably complete specimens. 
Family HEMIASTERIDAE 
Genus PERICOSMUS L. Agassiz 
PERICOSMUS MELANOSTOMUS, new species 
Locality.—Station 5302, China Sea, near Hongkong (lat. 21°42’ N., 
long. 114°50’ EB.) ; 70 meters; August 9, 1908. One specimen. 
Type —U.S.N.M. No. E.7153, from station 5302. 
Description.—The specimen, which is in good condition except some- 
what bleached, is a young one, only 12 mm. long, the genital pores still 
wanting. That it represents a new distinct species is, however, beyond 
doubt. The fact that I dredged in 1922 in the Sunda Strait a goodly 
number of specimens in every respect agreeing with the specimen col- 
lected by the Albatross serves to confirm the validity of this species, 
the second recent species of the genus Pericosmus made known. 
The test is egg-shaped, the oral side convex, not flattened ; the frontal 
’ depression is very shallow (more pronounced in larger specimens). 
The posterior edge is vertical, the periproct close to the upper edge. 
The petals are only slightly sunken, short, but rather broad; the 
posterior only about half as long as the anterior petals. Frontal am- 
bulacrum somewhat broader than the petals, tube feet large, with a 
