188 HAWAIIAlf AXD OTHER PACIFIC ECHINI. 



The madreporic body is divided into two plates, the larger being rectangu- 

 larly elongated transversely, forming the proximal base of the genital plate ; 

 the smaller is pentagonal and adjoins the odd anterior ocular plate. 



The actinal system measures 32 ram. in greatest diameter. It is covered 

 with twelve or thirteen rows of imbricating concentric ambulacral plates, 

 each carrying a horizontal row of small secondaries (PI. 80, fig. i). The 

 plates do not extend quite to the teeth, and diminish rapidly in size from the 

 base of the corona where they overlap sideways and vertically. A wide, 

 bare, triangular space is thus left between each set of ambulacral plates 

 (PI. 80, fig. 1) next the teeth, much as in A. thetidis, but not quite as 

 marked as in that species (PI. 70, fig. 2). 



The pedicellariaB of pyrochloa are so nearly like those of liystrix that no 

 extended description is necessary. The large tridentate (PI. 66, fig. 1) have 

 the valves .80-1.75 ram. long, while in the small trideiilate (fig. 2) they are 

 only .70-.85 ram. in length. The triphyUous pedicellarioe (PI. 66, fig. 3) are 

 very small, on very slender stalks ; the valves measure only .30-.40 ram. in 

 length. The sphceridia are somewhat club-shaped, .50-60 mm. long. The 

 calcareous spicules in the tube-feet are very numerous perforated plates of 

 irregular form and size ; some are nearly half a millimeter in diameter, and 

 have about a hundred perforations. 



This species was taken by the " Albatross " at the following stations, the 

 specimens ranging from 100 to 195 mm. in diameter : 



Station 4919. Off Kagoshima Gulf, Japan ; 30° 34' N., 129° 19' 30" E. 

 Bott. temp. 41.8°. 440 fathoms. Glob. oz. 



Station 5086. Off Joka Sima Light, Japan; 35° 8' 15" N., 139° 20' E. 

 Bott. temp. 43.7°. 292 fathoms. Gn. m., crs. bk. s. 



Three specimens. 



Araeosoma Belli Mortens. 



AathenoBoma hystrlx A. Agassiz, 1874. " Hassler " Ech., Mem. M. C. Z., IV, p. 3 ; PL 



II, fif,'s. 1, 2. 1880. Bull. M. C. Z., VIII, p. 74. 

 AraeoBoma Belli Mortenseu, 1903. " lugolf " Ech., I, p. 55. 



Caribbean Sea; 103-140 fatljoins. 



Plate 66, fig. 5. 



Although Mortensen's species is based on the characters shown by the 

 pedicellariaB, we find that the peculiarities of the test, pointed out in 1874, 



