124 HAWAIIAN AND OTHER PACIFIC ECHINI. 



There appear to be three quite distinct species in the group, of which granu- 

 latum Mortensen is from the East Indian region, ranging from the Maldives 

 to New Guinea, in 10-120 i&\hoTC\s; japonicmn Mortensen is from Sagami 

 Bay, Japan, 30' fathoms ; and pallidum A. Agassiz and Clark is from the 

 Hawaiian Islands, in 123-220 fathoms. These species mny be distinguished 

 as follows : 



Color of test and spines brown ; Vilue spots or a blue line along each side of 

 bare, abactinal, interambulacral space. 



At ambitus, in each interambulacrum, 10-12 columns of primary tu- 

 bercles ; most of actinal surface densely covered with secondary and 

 miliary tubercles, and without primaries; blue spots at sides of ab- 

 actinal interambulacra granulatum. 



At ambitus, in each interambulacrum, 6-8 columns of primary tubercles ; 

 most of actinal surface with primary tubercles ; a blue line at sides of 



abactinal interambulacra japonicimi. 



Color of test buff ; spines whitish ; primaries often more or less banded with 



purple ; no blue anywhere ►- pallidum. 



Chsetodiadema pallidum A. Ag. and CI. 



Chaetodiadema pallidum A. Agassiz and Clark, 1907. Bull. M. C. Z., L., p. 237. 

 Plates 44, figs. 5, 6 ; 50, figs. 16-19 ; 56 ; 59. 



Of the interesting genus Chaetodiadema Mortensen a handsome new 

 species proves to be common in certain localities among the Hawaiian 

 Islands (Pis. 56, 59). As stated by Mortensen* of Ch. granulatum, the test, 

 when seen from above, resembles closely that of Astropyga, but in our 

 species the test has not the flexibility of that of the Echinothuridae. 



In the tuberculation of the actinal surface this species is more closely 

 allied to Ch. japonicmn Mortensen (1. c. PI. 2, figs. 16,19) than to granulatum 

 Mortensen (1. c. PI. 1, figs. 1 3, 21, 22), as the former species does not 

 have the whole actinal side covered by such close and fine uniform granu- 

 lation (see PI. 59, fig. 3, and Mortensen 1. c. PI. 2, fig. 19). As Mortensen has 

 given no detailed figures of either the actinal or abactinal systems, nor of 

 the peculiar arrangement of the tuberculation on the actinal surface of the 

 test, it is difficult to compare our species with the two he has described. It 

 is apparent, however, by a comparison of the photographic figures of Ch. 

 pallidum on PI. 59 with his figures on PI. 1, and on PI. 2, that pallidum 



» Danish Exp. to Siam : Echinoidea, p. 22, 1904. 



