REPOET ON THE ECHINOIDEA. 67 



small plate covered with miliaries, and each carrying slender spines, arranged in thick 

 tufts (PI. VIII. figs. 1, 4, G), so that in specimens which are not denuded, the whole 

 abactinal system is thickly covered with miliary spines (PI. VIII. fig. 1). There are in 

 specimens measuring 1 6 mm. in diameter only eight or nine interambulacral plates, each 

 carr}'iug only one large primary tubercle ; the scrobicular area occupies, as in the Cidaridae, 

 nearly the whole of the plates (PL VIII. fig. 5), the rest of the plate being fiUed with 

 miliaries of uniform size, arranged much as in the Cidarid^. In the ambulacral system 

 there are from four to five small primary tubercles, increasing in size from the actinostome 

 to the centre of the test, forming two short vertical rows much as in Hemicidaris. When 

 alive the colour (in specimens collected by the " Blake ") of the miliary spines covering 

 the test is yellowish-pink, the primary spines somewhat darker, or of a light violet tint. 



Off Macio ; 1700 fathoms. September 11, 1873. 



Station 170. July 14, 1874. Lat 29° 45' S. ; long. 178° 11' W. ; 630 fathoms; 

 bottom temperature, 4'0° C. ; rocks. Kermadec Islands. 



Station 171. July 15, 1874. Lat. 28° 33' S. ; long. 177° 50' W. ; 600 fathoms; 

 bottom temperature, 4'0° C. ; rocks. 



Off Cebu ; 100 fathoms. 



Echinothrix. 

 EchinotTirix, Peters, 1853, Monatsb. Akad. Berlin. 



Echinothrix calamaris. 



Echinus calamaris, Pall. 1774, Spic. ZooL 



Echinothrix calamaris, A. Agassiz, 1872, Revis. EcL, part 1, p. 120. 



Kandavu Reef. Fiji Islands. 

 Tahiti Eeef. 

 Cebu Eeef. 



Echinothrix turcarum. 



Diadema turcarum, Schynv., 1711, Thes. Imag. 

 Echinothrix turcarum, Peters, 1858, Monatsb. Akad. Berlin. 



Honolulu. 

 Kandavu Reef. 



* Micropyga. 



Micropyga, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 200. 



This genus, with its flattened test and short spines, is closely allied to Astropyga, from 

 which it mainly differs in the small size and the structure of the abactinal system, which 



