80 HAWAIIAN AND OTHER PACIFIC ECHINI. 



The sphseridia (PI. 49, fig. 9) are a trifle longer than wide. Their position 

 and arrangement are the same as in scutata. 



This species was taken only at : 



Station 3973. Near French Frigate Shoal; 23°47'10" N., 166°24'55" W. 

 Bott. temp. 41°. 395-397 fathoms. Crs. co. s. sh. co. r. 



Habrocidaris scutata A. Ag. and CI. 



Podocldaris scutata A. Agassiz, 1880. Bull. M. C. Z., VIII, p. 72. 

 Habrocidaris scutata A. Agassiz and Clark, 1907. Bull. M. C. Z., L, p. 234. 



Plate 49, figs. 15-20; 54, figs. i-9. 



This species was not taken by the " Albatross," but is included for com- 

 parison with the preceding. 



The test of the specimen figured in plate 54 is silvery with a brownish 

 tinge. The diameter is 17.5 mm., height 9 mm. The striation of the 

 plates, so marked in the abactinal system of Salenia, and on some of the 

 abactinal coronal plates of Dialithocidaris and of youthful stages of Arbacia, 

 is slightly seen in H. argentea, but is very marked in H. scidata. The short 

 club-shaped granules of the abactinal parts of the test are irregularly scat- 

 tered over the abactinal system (PI. 54, fig. 5). They are far more numerous 

 than in H. argentea, and on the abactinal interambulacral plates they are 

 arranged in irregular lines parallel to the sutures. These lines are most 

 prominent at the equatorial belt (PI. 54, fig. 5), but have nothing of the 

 prominence and regularity which distinguishes Podociclaris. The abactinal 

 system is pentagonal, but less so than in H. argentea, the genital plates 

 shorter and the ocular plates comparatively larger and higher (compare figs. 

 5 and 2, PI. 54). The niadreporic genital is the largest and has its pore placed 

 in a slightly raised protuberance much as in Tiarechinus.^ There are five anal 

 plates. The actinal ambulacral plates are chiefly compound plates only one 

 or two of the four or five which carry no tubercles (PI. 54, fig. ^), being simple 

 plates as in P. argentea (PI. 54, fig. 1). In two of the ambulacra one of the 

 actinal plates carries a minute tubercle, while on each of the next five plates 

 a large tubercle is found near the lower median angle of the plate (PI. 54, 

 figs. ^, 6). The plates are provided with three (or rarely four) pairs of pores. 



1 See p. 181, fig. a, Dod. " Valdivia" Echini. 



