DISTANT RELATIONS. 99 



in every particular the ascidian larva, with 

 which, indeed, Kowalewsky and Professor 

 Ray Lankester have demonstrated its essen- 

 tial identity. But since a great many people 

 seem wrongly to imagine that Professor 

 Lankester's opinion on this matter is in some 

 way at variance with Mr. Darwin's and 

 Dr. HaeckeFs, it may be well to consider 

 what the degeneracy of the ascidian really 

 means. The. fact is, both larval forms that 

 of the frog and that of the ascidian com- 

 pletely agree in the position of their brains, 

 their gill-slits, their very rudimentary back- 

 bones, and their spinal cords. Moreover, we 

 ourselves and the tadpole agree with the 

 ascidian in a further most important point, 

 which no invertebrate animal shares with us ; 

 and that is that our eyes grow out of our 

 brains, instead of being part of our skin, as in 

 insects and cuttle-fish. This would seem a 

 priori a most inconvenient place for an eye 

 inside the brain ; but then, as Professor 

 Lankester cleverly suggests, our common 



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