239 



Neither time nor space permits me to enter on a detailed discussion of 

 the phylof^eny of Kchinoderms. I must content myself with slating 

 my perfect as^reemenl with Bather's views on this matter '). ( I would 

 only call attention to the difficulty pointed out already by Bury 2) that 

 no stage of fixation occurs in I he embryogeny of I^chinoderms, excepting 

 the Crinoids: Uio fixation of Brachiolari* by means of the sucking disk 

 is, as hinted at by Bury, evidently a secondary adaptation, which hardly 

 counts in this connection ). Consequently 1 am decidedly opposed to 

 the theories of the ancestry of Kchinoderms more recently set forth by 

 A. H. Clark ^) and J. E. V. Boas ^) — not to mention that of Simroth ^). 

 In my memoir on the development of Crinoids 1 have objected lo some 

 few points in the theory of Clark — who maintains the barnacles to be 

 the ancestors of l^ciiinoderms; but otherwise I do not think this theory 

 more worthy of a refulalion than thai of Simroth, deriving the h>chino- 

 derms from Mijzosloina! My few counter-remarks to some of the inter- 

 pretations of Crinoid morphology, set forth — rather emphatically — by 

 A. H. Clark on the base of his Iheorv, are meant as a tribute called forth 

 by my admiration for the eminent specialist in Crinoids, not as a wish 

 lo refute his theory, which seems to me a superfluous task. Both the said 

 theories, besides bearing evidence of most unusual conceptions of mor- 

 phology, are at variance with the fundamental principle of phylogeny, 

 that evolution goes from the lower towards the higher organization, not 

 the inverse way (due allowance being made, of course, foi- I he rarer cases 

 of regressive development, as e. g. the Acoela, which is, however, only an 

 ajiparenl exception to the rule). 



This objeclion does, of course, not ap[)ly lo I lie theory of Boas, thai 

 the Kchinoderms have develo|)ed from some fixed form of Coelenlerates: 

 but otherwise this theory is, in my opinion, no more acceptable than are 

 those of A. H. Clark and Simroth. As slated above. 1 cannol enter on 

 a detailed discussion of the reasons given for this theory. Iml musl con- 

 fine myself lo making a few objections, which, however, wouhi appeal' lo 

 suffice for ])roving Ihe unleiiabilily of the theory. 



One of the main fads adduced by Boas as support for his theory is this 

 thai in the Crinoids -- and, mind well, nol Ihe more primitive Pelmalo- 

 zoa, the (Astids, the simpler forms of which, at least, do nol show any 

 external signs of a radiate structure') — the water-vascular system re- 



') F. A. Bat her. HchiiuxliTiiKi, in Ray I, anki-st er's Treatise on Zoology. Fart III. 1000. 

 -) H. Bury. 'I'lie nu'taniorpiiosis of Kchinoilcrnis. Quart. .lourn. .Micr. Sc. 38. 180,"). p. 03. 

 ») A. H. ciark. A Monograph of Existing Crinoids. I. U. S. Nat. Mus. Bull. 82. lOl.".. 

 ♦) J. K. v. Boas. Zur .\ulTassung dor Verwandtschafts-Verhaltnisse dor Tiere. I. 1017. 

 *) H. Simroth. t^ber den L'rsprung di-r Hchinodernien. Verh. d. Deutsch. Zool. Ges. 1904. 

 ') The radiate structure of Echinoderms is regarded as requiring their derivation from 

 "einer ex(|uisil radiiir gebauten .\bteilung festsitzender riere " (Op. cit. p. 21). 



