REPORT ON THE ECHINOIDEA MORTENSEN 



271 



121° 42' 15" E.); 570 meters; bottom temperature 9.61° C; gray 

 mud and globigerina ooze; June 3, 1908 (1 specimen, the type, Cat. 

 No. E. 1351, U.S.N .M.). 



Measurements 



Fig. 13.— Part of apical system of Goniocidaris (Cyrtocidaris) 

 tenuispina, new species, var. major, new variety. xt> 



Characters. — This specimen differs in certain respects both from 

 the typical form and from the variety tuberculata. 



In the first place its larger size is noteworthy, 29 mm. in horizontal 

 diameter as against at most 22 mm. in the typical form. This does 

 not simply mean that 

 it is older and there- 

 fore larger. It must 

 be kept in mind that 

 the species of Gonio- 

 cidaris develop the 

 apical disks only on 

 the uppermost spine 

 in each series of pri- 

 maries, and accord- 

 ingly, when the disks 

 have been formed, the specimens must be assumed to have reached 

 their full size. The specimen of the typical form in which the apical 

 disks have appeared in all the series, not only in one series in each 

 interambulacrum, measures only 22 mm. in horizontal diameter; but 

 the specimen from station 5259 measures 29 mm. in horizontal diam- 

 eter and has still only developed the first circle of the disks and thus 

 evidently has not yet reached its maximum size. Then the primary 

 spines are distinctly thicker than those of the typical form, 2.5 mm. 

 in diameter at the base, against 1.5-1.8 mm. Also the spinules of 

 the primaries are distinctly smaller than in the typical form ; further, 

 the fact that the spinules are distinctly larger in the outer part of the 

 spine is a conspicuous difference from the type. The hair covering is 

 somewhat denser but otherwise essentially like that of the type. 



In regard to the test and the secondary spines I hardly find any 



noteworthy differences from the typical form; but the oculars are 



more elegant in outline and not triangular (fig. 13 to compare with 



fig. 10), and the scrobicular tubercles are slightly larger. The pedi- 



27566—27 3 



