64 



THE VOYAGE OF H.M.S. CHALLENGER. 



prominence, which is more protuberant both in Gonodactylus glabrous and in Gono- 

 dactylus graphurus than it is in Gonodactylus chiragra. 



The very close resemblance between the three species shows their close relationship, 

 and it is quite possible that future discoveries may reveal so many transitional forms 

 that the sharp hues between the species will break down, but in the present state of our 

 knowledge of the group I think we are compelled to recognise the three as distinct 

 species. 



