202 bulletin: museum of comparative zoology. 



Primaries greenish, often cross-banded with darker, stout, about 

 equal h. d. ; thickness 8-12 % of length ; covered with 12-13 

 longitudinal series of coarse, sometimes sharp granules ; collar 

 light reddish or whitish ; secondaries greenish, with a broad 

 longitudinal stripe of brownish- or purplish-red at tip; triden- 



tate pedicellariae common dubia 



Median ambulacral and interambulacral areas not at all bare. 



Coronal plates 4 or 5, rarely 6 even in large specimens; primaries 

 slightly swollen near base, terete, almost smooth ; large globifer- 



ous pedicellariae wanting calacantha 



Coronal plates 6-8, rarely 5 even in small specimens; primaries not as 

 above. 

 Areolae very small, those on largest coronal plate only .60-65 of 

 length of plate ; abactinal system .40 h. d. and actinostome 



.35 h. d perplexa 



Areolae moderate or large, those on largest coronal plate .70-75 of 

 length of plate ; abactinal system about .50 h. d. and actino- 

 stome about .45 h.d. 

 Primary spines somewhat flattened, at least near base, with about 

 10 longitudinal series of coarse, sharp granules which usually 

 become fused near tip into ridges ; in old specimens these 

 ridges may occupy entire length of spine, no separate gran- 

 ules being visible, while in other cases granules may be con- 

 spicuous as sharp prickles almost entire length of spine; 

 primaries white or whitish, spotted or banded with brownish- 

 red or purple ; collar very narrow bracteata 



Primary spines terete, witli 12-15 longitudinal series of fine, sharp 

 granules which do not lose their individuality entirely, even 

 near tip of old spines ; unicolor, white or pale yellowish ; collar 

 of moderate width reini 



Tretocidaris tiara. 



Dorocidaris tiara Anderson, 1894, Journ. Asiat. Soc. Bengal, 63, p. 188. 



Plate 5, figs. 2, 2a, 111. Investigator Zool. E<h., Alcock and Anderson, 1895. 



This is one of the species collected by the " Investigator," the real position of 

 which is somewhat doubtful, although the figures given in " Illustrations . . . 

 Zoology . . . Investigator" (1895, pt. 2, plate 5, figs. 2 and 2a) indicate its 

 position in Tretocidaris. The test is extraordinarily high, even though the 

 measurements given by Anderson represent some other method of estimating 

 the height of the test than that which is here used. There are several reasons 

 why tiara is not synonymous with St. indica DoJerlein, as has been suggested, 

 but it is still more incredible that it should be T. bracteata, as Mortenseu (: 03, 

 p. 173) asserts, unless Anderson's description and figures are to be entirely 

 ignored. Either Mortensen has not seen a specimen of bracteata, or else his 

 supposed specimen of tiara is not tiara at all. Anderson's figures and descrip- 

 tion are remarkably clear and complete, and unusually satisfactory, although he 



