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SCIENCE 



[N. S. Vol. XXXIII. No. 843 



its place during all the procedure of fos- 

 silization. We can not say how enduring 

 this condition of deject dependence was in 

 the life of the individual of the Silurian, 

 but the Devonian faunas and more espe- 

 cially those of the early Carboniferous 

 when the crinoidea attained their maxi- 

 mum profusion, at once furnish abundant 

 and well-knOwn facts indicating that this 

 habit had at least become so fixed that it 

 began with a very early juvenile stage and 

 continued probably till released by death. 

 The domes of many crinoids in these 

 faunas have shown by successive elliptical 

 scars, of which the proct is the focus, left 

 by growing shells, that the snail remained 

 permanently and solidly devoted to this 

 habit for probably all the later stages of 

 its life. This is distinctly a case of true 

 parasitism; not merely of that degenera- 

 tion resulting from dependence which is 

 universal in nature, but of absolute and 

 abject dependence on the vital functions 

 of another. During the maximum of the 

 crinoids as well as of these capulids or 

 limpets in the early Carboniferous time 

 the attachment seems to have been not 

 occasional, but to have attained the char- 

 acter of an actual habitude to which all 

 members of the Capulids were liable even 

 though not all really practised it. This 

 singular condition endured during millions 

 of years from its inception in the Silurian 

 to its climax, but from the time of its 

 general prevalence in the early Carboni- 

 ferous on through the closing stages of 

 the Paleozoic and through the long follow- 

 ing ages up to the present we seem to lack 

 any shred of evidence of its continuation. 

 In very fact it seems as if in the long pano- 

 rama of life through the varying phases of 

 this great time interval, for the first time 

 in all our knowledge of the parasitic life 

 in all circles of existence (except where 

 this has been influenced by the higher 



motives which govern humanity) , that here 

 nature had demonstrated the power in her- 

 self to rebound from such tendencies to 

 degeneration, to give her creatures a sharp 

 turn about and start them again on the 

 upward path. What a splendid signifi- 

 cance of salvation it would be for the tre- 

 mendous majority of nature's apparently 

 doomed races if there should lie herein 

 even a slender ray of hope for the recovery 

 of tendencies toward the normal upward 

 progress which so many organisms have 

 lost by the supei'vention of degenerate hab- 

 its. We may not be entirely sure that this 

 ray of hope for a lost nature really exists, 

 for even though we have no evidence 

 of the parasitic dependence of the gastro- 

 pods upon the Bchinoderma in all the ages 

 of the Mesozoie and the Cenozoic, we do 

 know that in the present sea all parasitic 

 gastropods are parasites on the Echino- 

 derma, the class to which the crinoids 

 belong. 



Crinoids are few to-day; to my knowl- 

 edge no one has recorded on them the pres- 

 ence of parasitic snails, but their close 

 relatives, the star-fish and sea urchins, are 

 still beset by gastropods, often so modified 

 by their degeneracy that their nature is 

 hardly recognizable, and this parasitism too 

 is fixed and beyond repair. In these cases 

 which have been particularly studied by 

 the Sarasin brothers, the parasite is still of 

 the limpet type of structure, whether the 

 host be starfish or sea urchin. There is a 

 palpable vast difllerence in degree between 

 this particular form of parasitism to-day 

 and the association of limpet and crinoid 

 in the days of the Carboniferous seas, the 

 later irremediable, the earlier still not be- 

 yond repair, well established but clearly 

 not beyond the control of the dependent. 

 The great gap of positive evidence in the 

 profoundly studied Mesozoie and Tertiary 

 faunas which certainly should have af- 



