HCHINOIDEA. II. 



Agassiz coinpares 3, 5 and 5, 9, whereas the most characteristic of them, fig. 22, is not meiitioned. 

 If Profesor Agassiz had compared tlie figure 3 witli fig. 9, and fig. 5 with fig. 22, as is the only 

 natura! way to conipare them, he would probably liave agreed with ni)- placing these species in two 

 different genera. Since Professor Doderlein now agrees with me in referring these two species to two 

 different genera, I think there eau scarcely be an\ more doubt of the correctness of that view. — Ou 

 the other hånd m\- genus Pctalocidaris. estabhshed for Gmiiocidaris florigcra. seems, indeed, uutenable, 

 as pointed out b\' Doderlein (p. 96). Tlie remarks by Agassiz on this genus (p. 22) are singularh 

 unfortunate. All the figures to which reference is made there are of Tretocidarix. The diagnosis of the 

 genus (p. 28) and a comparison of the figure of a large globiferous pedicellaria (PI. X. 27I with that 

 of Goviocid. tnbaria (PI. X. 20) would have shovvu that the genus was not based on the small opening 

 of the point of these pedicellariæ but on the elougated form of the blade. 



The association of Dorocidaris hrnctrata A. Ag. with St<-phanocidaris bispinosa uia\' be wrong, 

 but having no specimeu of the former at my disposal I am miable to sa\' anythiug definite; since 

 Professor Doderlein has now completely altered the position of Strplianocidaris bispiuo.sa by tinding 

 its large globiferous pedicellariæ, of the form without end-tooth typical of the genus Cidnritfs Lamarck 

 (Cidaris Klein in Part I of this work), the form taken b\ me to be the large globiferous pedicellariæ 

 being, in faet, the small form, it is probable that I have likewise (jul\' seen the small form of globiferous 

 pedicellariæ in Dorne, bractcata. But as long as we do not know the large globiferous pedicellariæ of 

 this species it is i-mpossible to say with certaint)" to which genus it belongs. The characteristic, that 

 the abactinal s\steni of Sfrpliaiiocidans bispinosa is somewhat more flexible thau in other Cidarids, 

 does not seem to me so extremely important as Agassiz holds it, since he finds it so entirely unique 

 among the Cidaridæ that there is no excuse for associating with it a species with the abactinal system 

 of the species of Dorocidaris (p. 23). On comparing vertical sections of tests of Stcphanocidaris bispinosa 

 and Dorocidaris papillafa I find that not only the apical system but the whole test is distincth' thinner 

 in the former. Certainh-, I cannot consider this difference a very important character. Professor Doder- 

 lein also evidently holds this character to be only of secondary importance, since he iniites Cidaris 

 hacitlosa and vcrticiUata with Stiplnnioc. bispinosa in the same subgenus. (Op. cit. p. loi.) 



Professor Agassiz evidently finds it too meaningless to deserve a refutation, wheu ou account 

 of a general resemblance I ventured to suppose that Dorocidaris panamensis had the same kind of 

 globiferous pedicellariæ as Cidaris a/jiiiis. If he had fouud it worth while examining these structures 

 he would have found that my suggestion was quite right', and he would ha\e axoided the erroneous 

 statement that this species is the Pacific representative of D. papillafa . 



P'or m\' suggestion that Goniocidaris canalictdata might be a Sfercocidaris Profes.sor Agassiz 

 can see no reason, especially since it is quite contrary to my principles to refer Hving species to 

 genera established for fossil species. To Mortensen affinities as usualh' recognized by most writers 

 on Echini have no iuterest and have uo valut- wheu not based on the pedicellariæ (p. 32). The cases 

 where I do refer living species to genera based on fossil species seem to me to show that I also 



' I havt had occasioii to examine spei'iuiens of this species, identified bv Professor Agassiz himself, in the U. S. 

 National lluseuiii. The only difference of some importance between the pedicellariæ of this species and those of C. ajfinis is 

 that no Unib of projecting rods is found on the stalk of the large globiferous pedicellariæ — at least not 011 the few I 

 have exaniined. Thev occur very sparinglv: I have only found them in two of the niiie speciinens examined by me in the 

 U. S. National Museum. 



