8 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Dorocidaris affinis A. Ag. 



Cidaria affinis Philippi, 1845. Arch. f. Naturg. Eilfter Jahrg. Bd. I, p. 351. 



Dorocidaris affinis A. Ag., 1869. Bull. M. C. Z., I, pp. 17 and 254; Rev. Ech. PL I, fig. 5. 



Plate 12^ figs. 1-3. 

 Mortensen^ has pointed out the characteristics distinguishing this species 

 from papillata, but he fails to realize the diversity which the pedicellariae 

 may show. It is true that the large globiferous pedicellariae are ordinarily 

 like those of Cidaris (PI. 12'', fig. 3), but occasionally they are scarcely dis- 

 tinguishable from those of Dorocidaris (PI. 12'', fig. 1), while not infrequently 

 they are somewhat intermediate as the opening is not quite terminal 

 (PI. 12^ fig. 2.). 



Dorocidaris Bartletti A, Ag. 



Dorocidaris BarUetti A. Ag., 1880. Bull. M. C. Z., VIII, 2, p. 69. 



Plate 12^ figs. G-13. 

 Of all the Cidaridae which we have examined, none exhibit more re- 

 markable diversity in the form of the large globiferous pedicellariae than 

 does this interesting and handsome West Indian species. Although the most 

 common form (PI. 12% fig. i^) is that which Mortensen - gives as the dis- 

 tinguishing feature of his proposed genus Tretocidaris, others (PI. 12', 

 fig. 7) are quite frequent which ought to distinguish a true Cidaris, while 

 others (PI. 12% figs. 6 and 9) are quite unlike either. The pedicellaria shown 

 in PI. 12*. fig. 6, may possibly be a stage of growth of the one shown in PL 12% 

 fig. 7, but this hardly seems probable. If one were to attempt to determine 

 the generic position of this species by the pedicellariir, it is obvious that 

 serious difficulties would arise, nor would the presence of a ""limb" on the 

 stalk be of assistance, for it is also a very variable character (PI. 12% figs. 12 

 and L3). This great diversity in the pedicellarite is of special interest 

 because the primary spines of Jiariid^i show a greater variety of form than 

 those of any other member of the genus, and according to Morteusen's 

 view'' the pedicellaria) ought to afford more constant characters. 



» IiiRolf F.xped. Ecliiuoidea, 1903, Pt I, pp. 35-37. 

 • Loc. cit.. p. 10. 

 ' Loc. cit., p. 15. 



