144 Bvlletin Vanderbilt Marine Museum, Vol. VII 



stations in the Dutch East Indies: Bima; Badjo Bay; Flores; 

 Laiwui, Great Obi Island; the coasts of Salawatti; Gisser; Kur 

 Island; Kei Islands: Aru Islands, Kulewatti, Dammer Island; 

 Banda; Amboina (Koehler), also Badjo Bay, Flores Island, 23 

 fathoms (H. L. Clark) and Durian Straits (Boone) ; Amboina 

 (Doderlein). Southeastward from the Red Sea this species is 

 found at Mauritius (Brock) and west Australia: Shark's Bay, 

 Albany, Oyster Harbor, (Koehler) which appears to be the south- 

 ernmost record of the species to date, and eastward to the Fiji 

 Archipelago, the type locality (Verrill, Lyman, Clark). 



Material examined : Three fine specimens, entwined on the 

 primary spines of two specimens of Prionocidaris baculosa vari- 

 ety mmulifera (Lamarck) , brought up on the anchor chain of the 

 yacht "Alva," in Seba-Seba Bay, South Brother's Island, Durian 

 Straits, Dutch East Indies, October, 1931. 



Technical description : The diameter of the disk is 4.7 mil- 

 limeters. The disk is subcircular, with the margin undulating; the 

 abactinal surface is almost entirely covered by six pairs of large 

 radialia, which are pear-seed-shape and have the two plates of 

 each pair lying side by side, with the apices acute, directed inward 

 and extending practically to the disk center ; the distal margins 

 are evenly rounded. The interradial area is greatly reduced, the 

 width of one section at the outer margin being equal to about one- 

 half the width of one adjacent radial plate and tapering inwardly 

 to a mere line at the apex. The entire abactinal surface is encased 

 in a tough integument, which under high magnification shows a 

 continuous pattern of low circular reticulations. In addition to 

 these there are numerous coarse, irregularly scattered, well spaced, 

 upstanding, blunt, thick, conical spinules or tubercles. At, or 

 adjacent to, the apex of each pair of radialia there is one such 

 spine which is twice as high and thick as the remainder. The 

 spines are also similarly placed on the interradial areas and near 

 the circumference of the disk they become more conspicuous. 

 These spinules are also very numerous at the base of each arm 

 where they appear to be set in approximate rows. 



The actinal surface has the interradial areas encased in a 

 tough skin which also covers the mouth-parts, so that their true 

 outlines are indistinguishable. The side mouth shields are approxi- 

 mately as large as the central shield with which they are closely 

 fused. The visible contour of the central shield appears squarish 



