"><) (iKotiKAI'IIICAL DISTUI HI TloN. 



M. Fischer concludes. " Is the doctrine of evolution over- 

 thrown by tlic facts ,M. liarrandc has produced '{ I do nol think 

 it. He has proved that there existed among the ancient ceph- 

 alopods two g real types. which have continued separate during 

 the entire period of their existence; but the evolution of each 

 of these types remains extremely probable, and conforms to 

 observations made upon them. In such matters one cannot, in 

 olfcei. ask more than a probability." * 



Geographical 



Most of the species of Octopods and the Nautilus are 

 littoral in habit, and have thence been conject ured to enjoy 

 but a limited distribution; and which is hold to jns'.ily the 

 multiplication of species. This reasoning is. however, falla- 

 cious, as it is well known thai many li.toral mollusks. not 

 nearly so well provided wiili means of swimming, have be- 

 come world-wide in distribution. I shall show hereafter, not 

 only that particular species of Odopns are known to inhabit ihe 

 shores of distant countries, bill tha 1 a large proportion of these 

 species which have been distinguished by slight and mutable 

 characters, and by their geographical distribution, will probably 

 need to be united when suiliciently s udied. This probable ex- 

 tensive distribution of living littoral species corresponds with 

 observations made upon fossil species of Ammonites. Nautilus 

 and other chambered genera, which are proved to have been 

 littoral in habit by their occurrence only in deposits representing 

 ancient sea-shores. Not to multiply examples amongst these 

 fossils, it may be ment ioned that Naiitilux xiiit/)lr.r -occurs in 

 Knropc. Kast Indies and Texas; that Ammo nil <>* Itnloimnji'imi.x 

 is found in Kuropc. Kast Indies, N. and S. Africa and S. 

 America; and that />Vr/////Vx (rnrt'jH* had even a o-reatei 1 distribu- 

 tion. Nevertheless, temperature has been observed to have 

 some eli'ect upon the distribution of the living oclopoda of 

 Kurope. similar bu! distinguishable forms or s|>ecies inhabiting 

 its northern seas, from those of the Mediterranean. As in .Mol- 

 luscan life generaHy. the development of specific forms has been 

 greatest in t ropical waters. 



* Jour, de Zool, iv, 419, 1877. 



