Vol. X, No. 6. J Indo- Australian Passnlid Coleoptera. 205 



[N.S.] 



Museunr Pt. vii, Crinoidea ; Calcutta 1912; pp. 18-19). That 

 so close a similarity should exist between groups so widely- 

 separated in the animal kingdom is sufficiently remarkable to 

 suggest that the phenomenon may be one of more widespread 

 occurrence. Louis Agassi z. in his "Essay on Classification" 

 (Boston 1S57, London 1S59), devotes section xxviii to the "Re- 

 lations between the Structure, the Embryonic Growth, the 

 Geological Succession, and the Geographical Distribution of 

 Animals p ' ; and Cope has considered the question from an evolu- 

 tionary standpoint in his essay on 'The Origin of Genera," 

 and in his notes on this essay in the introduction to his volume 

 of collected essays entitled "The Origin of the Fittest' ' (New 

 York, 1887, pp. vi-vii and 112-123). But neither of these 

 authors appear to have been aware that the relation of distri- 

 bution and structure is ever so detailed as it can be shown to 

 be in the groups noted above. These are the only additional 



references to the subject that I have yet been able to find. It 



is, however, less easy to trace the scattered literature of a 



question of this kind, than it is to trace that of systematic 



zoology, and I shall be greatlv indebted to anyone who will 



give me references to any other published work on these 

 lines. 



With regard to the Thelyphonidae only a preliminary note 

 has yet been published (loc. cit.), and the details have not yet 

 been fully worked out. The work of Austin H. Clark on Crinoids 

 is, however, most interesting in this connection. In discuss- 

 mg the relative ages of the recent crinoid faunas of different 

 seas (loc. cit.), he bases his conclusions on the degree to which 

 the centrodorsal plate differs from its primitive form, in adults 

 of species of Comasteridae found in different regions. He 

 finds the greatest difference in the majority of Australian and 

 East Indian forms (especially the former), somewhat less 

 difference in African forms, and least difference of all, in 

 the same geographical direction, in West Indian. In other 

 geographical directions relatively " young" {i.e. primitive) 

 faunas are found in Japan, in the Antarctic and thence north- 

 ward along the American coast, and in the Arctic. He says, 

 moreover (p. 18) : " This [the connection between distribution 

 and structure] holds good regardless of the subfamily or genus 

 to which the species may belong, and exactly the same thing 

 may be worked out in regard to other characters in this family, 

 and with other chara ters in other families." 



Another point brought out alike by the study of Crinoids 

 and of Passalids is the existence, in differ nt groups of species, 

 of one particular species which greatly exceeds all others both 

 in its geographical range and in its variability. But both 

 here, and in the relation of distribution to specialization, the 

 conformity of the two groups seems to be less deep than the 

 striking character of this conformity would lead one to 



