26 ' ECHINOIDEA. II. 



not think that aiiy single character shonld be made the basis of a classification or that a distance of 

 even hundreds of miles of sea-bottom is sufficient evidence of specific distinctness (p. 167). I must 

 refer in answer to what lias been said above (p. 10) against Professor Agassiz' characterizing my 

 classification as being based on a single character, and also to the above remarks on Professor de 

 Loriol's objections. As for taking even hundreds of miles of sea-bottom as sufficient evidence of 

 specific distinctness, I absolutely agree with Professor Bell, and I am sure he will be unable to point 

 out au\- of the species described b\- me as being based upon geographical distance aloiie. But, on the 

 other baud, I think Professor Bell will agree with me that great geographical and bathymetrical 

 distance ought alwavs to make one careful iu referring specimens to a species otherwise known only 

 from auother region, and only to identif\' them with such species on finding after a careful stud>- of 

 all available characters that the\- cannot be distinguished. I, for m\- part, do recognize sorae species 

 of Echini as almost cosmopolitan iu tlieir distribution, e. g. Heriiiaster cxpergihis (see also my remarks 

 on Echinocardium cordatuvi in this Part), though I do not recognize Echinns iiorvcgicus as a cosmo- 

 politan species, as it was made by Professor Agassiz. 



Professor Bell' s remark that the present condition of the family EcJiiiiothuridæ .<does not 

 warrant auy addition to it that need not be made (p. 169), does not seem to me quite warranted; at 

 least it seems to me that it is eas\- enough to refer the species to the genera as diagnosed by me 

 whereas it was extremely difficult iudeed to distinguish between P/ioniiosouia and Asthcnosonia after the 

 old fashion. And when Professor Bell exprcsses the hope that Professor Agassiz by means of his 

 large collections will be able to give us a definite idea of the range and character of the variation» 

 of the EcInnofJiiiridcT. I must sa>' that, if the miuute differences are not taken into consideration, I 

 fear the variations will not be very reliable. The generic value of characters found in pedicellariæ 

 may, of course, be disputed; but we eau be quite sure that specimens of the same species do not have 

 pedicellariæ of ver}' different structure, so that these minute characters, so easily seen with a very 

 little technical skill, should at all e\ents never be despised. 



Lambert' remarks: «Sans nier la valeur des caractéres fouruis paz les orgaues caducs et mi- 

 croscopiques de TEchinide, j'estime que leur nomenclature doit surtout étre fondée sur uu ensemble 

 de caractéres observables, aussi bien chez les fossiles que chez les \ivants, car la phylogénie est aussi 

 indispensable que Tembryogénie å l'e.xacte compréheusion des formes actuelles. Il ne faut pas appliquer 

 å des auimaux iuférieurs, dont les orgaues sout moius spécialisés, une méthode qui peut étre excellente 

 pour des étres tres évolués et perfectiounés, mais qui, pour les Echinides, fausse toutes les analogies 

 en placant dans des families différentes des formes aussi voisines que Loxcchiiiiis et Stroiigyloccutrotiis, 

 que Parasaknia et Gouiopygus . For the rest, he states that he agrees with Agassiz iu his views 

 on my classification. — The claini that the classification of Echini has to be founded on characters 

 also observable in fossil forms is, so far as I can see, unscientific. It is quite nnpossible to say a priori 

 which character will be of primary importance for classification. Onl\- by a careful comparative exam- 

 ination of all the characters presented by the animals in question eau it be decided on which of 

 these characters the classification has to be founded. When it is proved that some organ which can- 



' In M. Boule et .\ Theveiiiii; l'ossiles de la cote orientale de Madagascar. .\niiales de Paléontologie. I. 1906. 

 P- 14 (561. 



