CLARK: THE CIDARIDAE. 219 



off Cape Colony in 278 fths. The largest measured 36 mm. h. d. The color 

 is gray, with a brownish tinge, the secondaries with darker tips, and the actiual 

 primaries whitish. 



Stereocidaris tricarinata. 



Stereocidaris indica var. tricarinata Doderlein, 1901, Zool. Anz., 23, p. 20. 

 Stereocidaris tricarinata Doderlein, 1906, Deutsche Tiefsee Exp. Ech., p. 112. 



Plate 9, Deutsche Tiefsee Exp. Ech., Doderlein, 1906. 



This species seems to be rather better defined than capensis, but as its validity 

 depends largely on the value assigned to certain features of the pedicellariae, there 

 is still room for some doubt as to its proper standing. The deformed specimen 

 to which Doderlein has given the varietal name teretispina is indeed very different 

 from the typical form, but as it was a parasitized individual, its peculiarities may 

 be pathological. The " Valdivia " collected tricarinata only in the vicinity of 

 Sumatra in 206-417 fths. The largest specimen was 54 mm. h. d. The color 

 of the test is dark reddish ; the primaries are gray with rosy necks ; the actinal 

 primaries whitish ; the larger secondaries have a dark spot. 



Stereocidaris alcocki. 



Dorocidaris alcocki Anderson, 1894, Journ. Asiat. Soc. Bengal, 63, pt. 2, 3, p. 191. 



Plate 5, figs. 3, 3a, 111. Investigator Zool. Ech., Alcock and Anderson, 1895. 



There can be little question of the validity of this species unless indica proves 

 to be even more variable than is supposed. If the published descriptions are 

 accurate (and there is no apparent reason for doubting them), the two species are 

 quite distinct. The " Investigator " took alcocki in the Laccadive Sea in 636 

 fths. It is a small species, only 25-26 mm. h. d. 



Stereocidaris ingolfiana. 



Stereocidaris ingolfiana Mortensen, 1903, Ingolf-Exp. Ech., 1, p. 38. 

 Plate 6, figs. 1-5, 11, Ingolf-Exp. Ech., Mortensen, 1903. 



It is rather curious that this very distinct and interesting species should not 

 have been described until so recently, for adult specimens are easily distinguished 

 from any other North Atlantic or West Indian species. Even when the primary 

 spines are missing or do not have the " wings " developed, the species may be 

 recognized by the very numerous slender secondaries and miliaries, and the more 

 or less elevated median ambulacral area, densely covered with minute tubercles. 

 Mortensen' s description lacks nothing, but in the table of measurements it is 

 evident that " height" is estimated in some variable way ; for while in a large 

 series of tests of such a variable species as D. papillata, for example, there is 

 sometimes a variation of 20% in the vertical diameter, Mortensen's measure- 

 ments would indicate a variation of 30% among 8 specimens of ingolfiana ; and 

 while papillata is occasionally .75 h. d. in height, Mortensen gives one speci- 



