2 6 ECHINOIDEA. II. 



not think that any single character should 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 has 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 

 I.oriol'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 any of the species described by me as being based upon geographical distance alone. But, on the 

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

 distance ought always to make one careful in referring specimens to a species otherwise known only 

 from another region, and only to identify them with such species on finding after a careful study of 

 all available characters that the} - cannot be distinguished. I, for my part, do recognize some species 

 of Echini as almost cosmopolitan in their distribution, e. g. Heviiastcr expergitits (see also my remarks 

 on Echinocardium cordatum m this Part), though I do not recognize Echinus norvegicus as a cosmo- 

 politan species, as it was made by Professor Agassiz. 



Professor Bell's remark that the present condition of the family Echinothurida does not 

 warrant an}- 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 easy enough to refer the species to the genera as diagnosed by me 

 whereas it was extremely difficult indeed to distinguish between Phormosonia and Asthcnosoma after the 

 old fashion. And when Professor Bell expresses 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 Echinothuridce, I must say that, if the minute differences are not taken into consideration, I 

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

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

 pedicellarise of very different structure, so that these minute characters, so easily seen with a very- 

 little technical skill, should at all events never be despised. 



Lambert 1 remarks: «Sans nier la valeur des caracteres fournis paz les organes caducs et mi- 

 croscopiques de l'Echinide, j'estime que leur nomenclature doit surtout etre fondee sur un ensemble 

 de caracteres observables, aussi bien chez les fossiles que chez les vivants, car la phylogenie est aussi 

 indispensable que l'embryogenie a l'exacte comprehension des formes actuelles. II ne faut pas appliquer 

 a des animaux inferieurs, dont les organes sont moins specialises, une methode qui pent etre excellente 

 pour des etres tres evolues et perfectiounes, mais qui, pour les Echinides, fausse toutes les analogies 

 en placant dans des families differentes des formes aussi voisines que Loxechiwus et Strongylocentrotus, 

 que Parasalcuia et Goniopygus . For the rest, he states that he agrees with Agassiz in his views 

 on my classification. - The claim 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 impossible to say a priori 

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

 ination of all the characters presented by the animals in question can 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 A Thevenin: Fossiles de la cote orientale de Madagascar. Annates de Paleontologie. I. 1906. 

 p. 14 (561. 



