156 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



tips, 3 or 4 along either lateral margin being the smallest, and a 

 series of 3 or 4 back of the furrow, nearly as long as the furrow 

 spines. Three longitudinal series can usually be discerned, the spine- 

 lets in the outermost series being similar to those of the actinal inter- 

 mediate plates. 



Mouth plates rather narrow, forming a salient inner angle. Mar- 

 ginal spines about 9, gradually increasing in size toward the inner 

 teeth, which are flattened and bladelike, the outer members being 

 compressed and similar to adambulacral furrow spines. The series 

 is continued along the lateral margin in 8 or 10 short terete 

 pointed spinelets. Suborals similar to the subambulacrals. 15 to 18 

 in number, in 2 series, one along the median suture and the other 

 intermediate and parallel to tlie outer margin but not reaching 

 the inner end of the plate. 



Madreporic body small, wholly concealed, a little nearer marginal 

 plate than center of disk and nearly in the middle of r. 



Tube feet with a conical button at tip. 



Type.— Cuii. No. 30531, U.S.N.M. 



Type-locality. — Station 5178, vicinity of Romblon Island, Philip- 

 pine Islands (lat. 12° 43' N.; long. 122° 06' 15" E.), 78 fathoms, fine 

 sand; 1 specimen. 



Distribution. — Known only from the type-locality. 



Remarks. — This is a well-marked species of Patag taster, differing 

 from the type P. nuttingi of the Hawaiian Islands in having shorter 

 rays, larger paxillae with much more numerous granules, in having 

 the paxillae arranged in very definite longitudinal series parallel to 

 tne radial series, which, with the adradial paxillae, are subequal to 

 the lateral plates, not smaller and irregularly arranged. The mar- 

 ginal plates are broader in sphaerioplax and the actinal spinulation 

 more delicate. 



This genus was established for a single species, but the group is a 

 well-marked one, for in addition to nuttingi and spJmerioplax^ I 

 have examined a third species dredged by the Albatross in Japan. 

 The resemblance between this Japanese species and Pseudarchaster 

 is very striking, as indeed is that of spliaeHoplax. But the pointed 

 tube feet, concealed madreporic body, and the character of the fur- 

 row comb are all different, the first character being the fundamental 

 one which places Patagiaster in the Astropectinidae. Although the 

 new species is less like Dipsacaster than is P. nuttingi., I still believe 

 that the relationship is ratlier close. 



Patagiaster differs from Dipsacaster in having the gonads con- 

 fined to the interradial regions, not festooned along the ray, in lack- 

 ing papulae on the midradial region and center of disk, and in hav- 

 ing the paxillar spinelets more granuliform, although this last char- 

 acter is partly bridged by Dipsacaster diaphorus. It differs from 



