116 Bulletin Vanderbilt Marine Museum, Vol. VII 



Archipelago, New Caledonia and Samoa. The "Ara" specimens 

 add another Philippine record for this highly variable species. 



Material examined : Two specimens, collected at Zamboanga, 

 Philippine Islands, January 16, 1929, by the "Ara." 



Colour: Vermilion. 



Discussion: This species, which has a more restricted dis- 

 tribution than P. nodosus (Linne) known from the same area, is 

 readily distinguished therefrom by the presence of a series of 

 prominent distal superomarginal and inferomarginal tubercles. 



The two specimens taken by the "Ara" differ conspicuously in 

 the number and form of the large acorn-shaped tubercles of the 

 carinal ridge of the abactinal surface ; such variation has been 

 previously discussed by Mr. H. L. Clark (1908), who had a more 

 extensive series of twenty-seven specimens from New Guinea and 

 Amboina, also by Mr. W. K. Fisher (1919), who reported the 

 large "Albatross"-Philippines series of thirty-five specimens. 



In specimen A of the present series (plates 33 and 34), there 

 are nine large primary tubercles in carinal series on each of four 

 arms, on the fifth arm eight large and one distal rudimentary 

 tubercle. No tubercles are present in the apical area. Inter-radial 

 large "acorn" tubercles occur one each in three instances, two in 

 the fourth, and three in the fifth interradial area. These tubercles 

 appear higher than their proximal diameter, but the very largest 

 tubercles have a basal diameter subequal to the vertical diameter ; 

 the less stout tubercles average from 0.15 to 0.20 percentum 

 greater height than the related proximal horizontal diameter. 

 They are variously with the apex blunt or pointed, the majority 

 of the tubercles being terminated by a blunt short conical spine, 

 or with a lesion indicating where the spine has been abraded. The 

 tubercles are covered by an almost continuous series of low, coarse 

 granules of varying size and shape. None of the primary radial 

 tubercles is bifurcate. Superomarginal spines are present, being 

 more conspicuously, but unequally developed on the distal 0.40 to 

 0.50 of each ray. Inferomarginal spines are present numerously 

 and are quite acuminate along the interbrachial areas. The large 

 primary radial spines are slenderer than those of Pentaceraster 

 nodosus (Linne). 



Pedicellariae are of two kinds : (a) the long, low, bivalve, slit- 

 like kind to be found on the trabeculae, and (b) small, erect. 



