206 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



sunken, closely covered with stout plates, 4 in each interambulacrum and about 

 10 pairs in each ambulacrum. Primary spines short, about equal to h.d., nearly 

 cylindrical, seldom tapering, but often flattened and widened at tip, covered with 

 14-24 longitudinal series of coarse, sharp granules; actinal primaries much as in 

 Cidaris and nearly smooth ; secondaries, long and narrow, but rather thick and 

 often with a deep longitud.nal furrow on outer surface at tip, which is thus crescent- 

 shaped in cross-section. Pedicellariae not peculiar; no large globiferous ones were 

 found, but small globiferous and tridentate, like those of dubia, are frequent. 

 General color of test decidedly greenish, especially abactinally; miliary spines 

 greenish ; secondary spines greenish with a broad longitudinal stripe of deep 

 reddish-purple; primary spines dull grayish with a bright olive-green base and 

 collar. Largest specimen, 50 mm. h. d. ; vertical diameter, 27 mm. ; abactinal 

 system, 20 mm. ; actinostome, 18 mm. ; longest spine, 40 mm., 3 mm. thick at base, 

 5 mm. wide at tip. 



In some ways this species is much like dubia, but aside from the differences in 

 the tuberculation of the test, the small areolae, abactinal system and actinostome, 

 and the short primaries with olive-green collar and conspicuously flattened tips, 

 are very characteristic of perplexa. The resemblance between the two species in 

 the color of the secondary spines is quite noticeable. Two of the five known 

 specimens of this species were collected by the " Albatross " in the Gulf of Cali- 

 fornia on a bottom of coarse sand, in 36-39 fathoms. The other three are said to 

 have been picked up on the shore of Clarion Island, the westernmost of the Revilla 

 Gigedo Islands. 



Tretocidaris bracteata. 



Dorocidaris bracteata A. Agassiz, 1879, Proc. Amer. Acad., 14, p. 197. 



Plate 10, figs. 1 and 2. 



This is apparently the East Indian representative of bartletti, though it is a 

 smaller species and obviously quite different. Mortensen ( : 03), on the supposed 

 characters of the large globiferous pedicellariae, places bracteata in Stephano- 

 cidaris, but as we have already seen, he probably did not have a specimen of that 

 genus for comparison. Moreover, the pedicellaria which he figures as a " large 

 globiferous " of bracteata is exactly like the small, globiferous pedicellariae of this 

 species, while the large globiferous pedicellariae of this species are actually like 

 those of Cidaris. However, these large ones are very infrequent and may be want- 

 ing, while the small ones are often very large, and it is apparently one of these 

 latter that Mortensen has figured as the characteristic pedicellaria of Stephanoci- 

 daris ! It seems to me that this serves as an illustration of the danger of relying on 

 the pedicellariae. This species is relatively small, the largest specimen being only 

 29 mm. h. d. The secondaries are pale purple or rose, with or without yellowish 

 tips, or flesh-colored with a longitudinal rosy stripe ; in old specimens those of 

 the ambulacra may be darker than those of the interambulacra, and thus noticeably 

 contrasted with them, and the abactinal system is dark brownish-red; the prima- 

 ries always show more or less clearly the dark markings, which are usually pur- 



