164 J. HOPKINSON ON BRITISH GRAPTOLITES. 



tolites. In the Sertulariadfe, and also in the Corynid^ and Lucer- 

 nariadje, the new polypites are developed at or near the distal end 

 of the coenosarc, so that the distal polypites are the youngest. The 

 hydrotheca is at first simply the cuticular investment of its poly- 

 pite, represented in the young bud merely by the outer layer of 

 the ectoderm; but gradually becoming " more and more widely 

 separated from the body of the polypite, and eventually opening at 

 its distal end to allow of the protrusion of the distal moiety of the 

 polypite." (Huxley.) We can trace even this in the graptolite, 

 for in the youngest specimens no apertures are visible. We see, 

 therefore, that in their development, and, as far as we know, in 

 their reproduction, as well as in structure, graptolites are nearly 

 allied to Sertularian Hydrozoa. 



In conclusion — Do graptolites throw any light on the question of 

 the day — the Darwinian theory of the origin of species ? Let 

 us see. 



The graptolite, a Hydroid zoophyte, has lived, and with it all its 

 class has died. The whole race has comj^letely disappeared, and 

 for countless ages not a trace, not a single species of its class, has 

 existed. Millions of years, it may be, pass away, and this class re- 

 appears — is re-created. Whence comes this recent class, the 

 Hydrozoa ? Can it have been developed " by means of natural 

 selection," from its fossil progenitor, the graptolite, when for ages 

 no Hydroid zoophyte has existed ? Or can the graptolite have 

 grown " by the pressure of external circumstances," out of its own 

 humble class into another and a higher one, and then but recently, 

 comparatively speaking, can this higher class have re-introduced, 

 by natural selection (or " pangenesis"), the class from which it first 

 originated ? I think not. 



No Darwinist, I think, could imagine a germ (or "gemmule ") 

 lying dormant from the Silurian to near the recent epoch, and then 

 acting in the production of species as before. No Darwinist, 

 again, would allow that a race could disaj^pear and give place to a 

 higher race, and that in its turn could evolve the same lower race 

 from which it originally sprung. No ! Each class has been 

 specially created — created at its own appointed time, and to fulfil 

 its own special purpose ; and not only each class, but each order, 

 each family, and, I believe, each genus. I will not presume to say, 

 each species, for we cannot yet define the limits of a species. 



