224 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Acanthocidaris curvatispinis. 



Cidaris curvatispinis Bell, 1893, Trans. Z06I Soc., London, 13, p. 303. 

 Acanthocidaris curvatispinis Mortensen, 1903, Ingolf-Exp. Ech., 1, p. 29. 



Plate 38, Trans. Zobl. Soc. London, 13, Bell, 1893. 



Nothing is known in regard to this species, except that Bell has figured the 

 entire animal and Mortensen the pedicellariae. The type specimen in the British 

 Museum, and a second specimen in Paris, are both from Mauritius and are 

 the only ones known. The type specimen is about 50 mm. h. d., with primaries 

 150 mm. long; many of the latter are banded near the tip with brownish 

 and yellowish. 



Acanthocidaris hastigera. 



Acanthocidaris hastigera A. Agassiz and Clark, 1907, Haw. Pac. Ech. Cid., p. 39. 

 Plates 37-43, Haw. Pac. Ech. Cid., A. Agassiz and Clark, 1907. 



In addition to the differences mentioned above, this species may be distinguished 

 from the preceding by the stouter primaries and their entire lack of any cross- 

 barring or bands of color. It was found by the " Albatross " to be common 

 among the Hawaiian Islands. When cleaned, the test is nearly white in young 

 specimens, with the median ambulacral area red, the actinostome decidedly green, 

 and the abactinal system dull greenish-red ; in older specimens the white is re- 

 placed by reddish-cream color, and there is little green evident anywhere. When 

 uncleaned the test is, like the secondaries, dark brownish-red, much lighter in 

 very young specimens. The largest specimen is 52 mm. h.d. ; the longest 

 primaries are 145 mm. All of the " Albatross" specimens were taken on sandy 

 bottom in comparatively shallow water, 23-222 fths. 



Acanthocidaris maculicollis. 



Porocidaris maculicollis de Meijere, 1903, Tijdsch. Ned. Dierk. Vereen. (2) 8, p. 1. 

 Plate 3, figs. 18, 19, Siboga-Exp. Ech., de Meijere, 1904. 



The secondaries of this species are described as having " a dark longitudinal 

 stripe," but the ground color is not mentioned. The four specimens collected 

 by the "Siboga" were all small (10-18 mm. h.d) and were evidently young 

 ones. They were taken at depths of only 39-53 fths , and at each of the 

 three stations mussel-shells formed a characteristic feature of the bottom. 



POROCIDARIS. 



Porocidaris Desor, 1854, Syn. Ech. Foss., p. 46. 



Test rather high, .60-.75 h. d. ; coronal plates, 7-9; areolae more or less sunken 

 and merging actinally ; median interambulacral area with vertical sutural region 

 somewhat sunken and bare ; ambulacra .18— .34 of interambulacra ; poriferous zones 

 very little sunken; median ambulacral area with a single marginal row of tubercles, 



