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BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



quite possible that these are not really baculosa. It is interesting to note that the 

 purple spots on the collar may merge together, not only longitudinally so as to 

 form parallel vertical lines, but also diagonally, so that the collar appears check- 

 ered with light-colored, diamond-shaped spots. These spots are occasionally 

 rounded, and then the color shows some resemblance to that of the primaries of 

 Stephanocidaris. Further evidence of the close relationship existing between that 

 genus and baculosa is found in the abactinal system of the latter, where some or 

 all of the ocular plates may be broadly in contact with the anal system. The 

 coronal plates are 8-10 or even 11 in the largest specimens (64 mm. h. d.), and 

 the color is brownish-red or purplish, but is quite variable. The geographical 

 range appears to coincide with that of imperialis. A remarkably handsome spine 

 of a Phyllacanthus, quite unlike any of baculosa which I have seen, in the Museum 

 collection from " lie Bourbon," inclines me to Mortensen's (:03) view that the 

 identity of baculosa and pistillaris is still open to question. If it is not doubtful, 

 this species ought to be called by the latter name, as it has precedence in La- 

 marck's work. Doderlein (:06), on the strength of Loven's ('87) descrip- 

 tion and figure, adopts the Linneau specific name cidaris for this species, quite 

 overlooking Loven's own statement (p. 146) : " Be that as it may, the species 

 name : Cidaris L., left to its fate by the author himself, is to be laid aside as 

 without validity, though of some historical interest." In the collection of the 

 United States National Museum there is a notably fine specimen (No. 14,032) 

 from the Boniu Islands, labelled " annulifera " ; the secondaries are very long, 

 with a deep brown longitudinal stripe, and the collar of the primaries has some 

 indistinct white spots as well as the characteristic deep purplish-red dots. It is 

 quite possible this is an undeserved species. In the same collection is a large 

 series of specimens from Aden (No. 21,459), which have been labelled by Dr. 

 Mortensen " Cidaris metularia " ; the primaries are remarkably short and stout, 

 much as in Cidaris, and as Mortensen did not clean an ambulacrum, it is not 

 strange that he failed to see the very characteristic porifeious zones. But it is 

 hard to understand how he overlooked the conspicuous purple spots on the collar 

 of the primaries. 



CHONDROCIDARIS. 



Chondrocidaris A. Agassiz, 1863, Bull. M. C. Z., 1, p. 18. 



Test much as in Phyllacanthus, but densely covered with minute tubercles bearing 

 miliary spines and small globiferous pedicellariae; median interanibulaeral area 

 very broad, generally .35-.40 of interambulaerum, nearly flat; ambulacra narrow, 

 only .20-.25 of interambulacra ; median ambulacral area covered with about eight 

 vertical series of tubereles, of which the marginal ones are slightly larger ; pores 

 horizontal, widely separated, connected by a groove. Abactinal system .35-40 h. d., 

 with ocular plates entirely excluded from anal system ; genitals broadly in contact. 

 Aetinostome about equal to abactinal system. Primary spines stout, nearly cylin- 

 drical, sometimes slightly tapering, about equal to, or somewhat exceeding h. d., 

 provided with stout, blunt, thorny projections, and often near the tip with longi- 



