76 
BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
flattened, fluted and serrated on the edges, and are comparatively smaller and 
more slender than in species of the allied genus Podocidaris. The diameter of 
the test of this specimen was 21 mm. when alive, The color of test and spines | 
is yellowish brown. | 
DIADEMATIDÆ, PETERS. i 
DERMATODIADEMA, A. Ac, 
This genus holds the same relation to Aspidodiadema which Echinothrix 
holds to Diadema. It differs from it in having only small secondary tubercles 
in the ambulacral areas while in Aspidodiadema there are large primary tuber- 
cles in the actinal region, as in Hemicidaris. 
Marked for its high test, the five large plates surrounding the anal opening, | 
o ? o O d | 
the great width of the ambulacral area, and the stout primary interambulacral 
Dermatodiadema globulosum A. Aa. | 
Plate V. Figs. 3, 4. | 
radioles, and the deep furrows of the scrobicular area. The longest speci- 
men collected measured 22 mm, in diameter, the largest primary radioles are 
nearly twice the length of the diameter of the test. 
Station No. 3381, north of Malpelo Island, in 1772 fathoms. 
143 
This species has a comparatively large apical system. The anal system is 
covered by a large number of small plates, a ring of seven or eight somewhat 
larger plates surrounding the anal opening. The greater number of specimens 
were about 20 mm. in diameter, the apical system measuring 14 mm. across. 
It is probable that Aspidodiadema antillarum, collected by the “ Blake,’ 
have to be transferred to Dermatodiadema, the lack of material inducing me 
to associate it with Aspidodiadema, although it possesses the miliary primary 
ambulacral tubercles characteristic of the genus Dermatodiadema. Test dark 
claret color, primary radioles pinkish. 
Station No. 
66 
3398, off Galera Point, in 1573 fathoms. 
Dermatodiadema horridum A. Ac. 
Plate V. Figs. 5-7. 
’ will 
3362, between Cocos Island and Mainland, in 1175 fathoms. 
3363, between Cocos Island and Mainland, in 978 fathoms. 
3364, between Cocos Island and Mainland, in 902 fathoms. 
3375, south of Malpelo Island, in 1201 fathoms. 
3376, near Malpelo Island, in 1132 fathoms. 
3381, north of Malpelo Island, in 1772 fathoms. 
33 
? 
3400, from Galera Point to Galapagos, in 1322 fathoms. 
3413, northwest of Culpepper Island, Galapagos, in 1360 fathoms. 
398, off Galera Point in 1573 fathoms. 
) 
