REPORT ON THE ECHINOIDEA— MORTENSEN 295 



varies to such a degree that no reliable distinguishing character can 

 be found here. 



Some of the specimens carry sea anemones, besides serpulids, 

 sponges, and other organisms, on their spines. 



STYLOCIDARIS REINI, var. RUBIDA, new variety 



Plate 63, figs. 2, 3; plate 74, figs. 6, 7 



Locality. — Station 5398; between Masbate and Leyte; Gigantan- 

 gan Island (S.) bearing S. 45° E., 2.7 mile distant (lat, 11° 35' 12" 

 N., long. 124° 13' 48" E.) ; 208 meters; green mud; March 15, 1909 

 (3 specimens, Cat. Nos. E. 1376, the type, E. 1377, U.S.N.M.). 



Characters. — This form again is especially characterized by its pri- 

 mary spines and their hair covering. In the largest specimen, measur- 

 ing 24 mm. in horizontal diameter, the longest spines are 60 mm. in 

 length, thus two and one-half times the horizontal diameter, and very 

 conspicuously banded with red and greenish white; the collar is green- 

 ish. They are very slightly thickened at the base, gradually taper- 

 ing to a rather fine point. The spinules are arranged in distinct 

 longitudinal series, but, especially on the adapical side where the spi- 

 nules are somewhat larger than on the adoral side of the spine, so dis- 

 tant from each other as not to form distinct ridges, each spinule 

 rising separately from the flat surface of the spine; especially on the 

 red bands these white spinules stand out very distinctly; their base 

 is rather broad, the spinule itself ending in a rather sharp point. 

 The surface of the spine otherwise is covered with a coat of fine, 

 short, simple hairs, which are more or less distinctly gathered into 

 small groups, much as in the typical form. 



The secondary spines are flat, not concave on the outer side as is 

 usually the case in the typical form ; the marginal ambulacral spines 

 are rather broader than is usual in the typical form. In regard to 

 the test it is noteworthy that the interporiferous zone is rather naked, 

 there being only a single small tubercle on each plate within the 

 marginal tubercle; this is placed at the lower edge of the plate (pi. 

 74, figs. 6, 7) . There appear to be no other points of difference from 

 the typical form. 



While the larger specimen, to which the above description refers, 

 differs rather markedly from the typical form, especially in its primary 

 spines, a second specimen, nearly as large, 23 mm. in horizontal diam- 

 eter (poorly preserved with all the spines broken), shows the charac- 

 ters pointed out above to a much smaller degree, being, in fact, quite 

 intermediate between the variety and the typical form. A third 

 specimen, of only 14.5 mm. in horizontal diameter, has the primaries 

 of the same conspicuous red color as in the largest specimen, but is 

 otherwise, of course, too young for a real comparison. The spinules 

 of the primaries are disposed so as to form true ridges. Finally, a 



