348 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Station 5254, Gulf of Davao, Mindanao, 21 fathoms, sand, coral, 3 

 specimens. 



Philippine Islands, Dr. E. A. Mearns, 3 specimens. 



OREASTER ALVEOLATUS (Pftrrler). 



Plate 101, fig. 1. 



Pentaceros alveolatus Pebriek, 1875, p. 243. — Koehleb, 1910o, p. 95, pi. 10, 



fig. 1; pi. 14, fig. 7. 

 Oreaster alveolatus Bell, 1884, p. 73. 



Notes on Philippine speciinens. — In 2 specimens (stations 5254 

 and 5141) the spines are absent from the interradial region of the 

 dorsal surface; in the others there are from 5 to 10 spines in each 

 interbrachial area, in addition to those of the midradial line and 

 apical area. The spines are for the most part very prominent, 

 slenderer than the tubercles of O. nodosus, and upward of 20 mm. in 

 length. The granules are absent, as a rule, from the tip, which is 

 conical and sharp. Those covering the lower part of the spine are 

 a little larger than the granules covering the plates, crowded, flat, 

 and polygonal. In the largest example, having R=170 mm., 

 3 of the 5 primary radial spines are double, and there are 

 3 spines within the apical area. In all the specimens the 

 interbrachial inferomarginal spines are poorly developed, and in 

 an example from station 5141 there is only a single small tubercle 

 in 2 interradii, but 2 to 4 prominent inferomarginal spines at the 

 end of the ray. The superomarginal spines are usually very promi- 

 nent, especially in a specimen from station 5146, where there are 

 upward of 14 on either side of each ray, most of them ending in a 

 bare, conical sharp point. In 2 interbrachia there is a single supero- 

 marginal spine. This specimen has 3 to 5 interbrachial infero- 

 marginal small, blunt, tuberculate spines. The trabeculae separating 

 the papular areas are well marked, except sometimes the transverse 

 ones of the series of areas just above the superomarginals, where the 

 areas may be partly confluent. Along either side of the ray, which 

 is naturally high, are 3 well-marked lines of papular areas, with 1 or 

 2 additional for a very short distance at the base of ra3^ The upper- 

 most series may be subdivided into 2 series of alternating triangular 

 areas, while the areas of the 2 lower series are rectangular, elliptical, 

 or irregular. 



In addition to long, low, bivalved, slit-like pedicellariae on the 

 trabeculae, there is a very variable number of small upright forceps 

 pedicellariae on the papular areas. The jaws of these vary in height 

 from about the length of the surrounding granules (Jolo) which 

 are subconical or convex, to twice the length (stations 5149, 5254) or 

 a little over. 



