EEPORT ON THE CEPHALOPODA. 



223 



The most remarkable instances of wide distribution are Octopus macropus (from 

 five regions), Octopus granulatus and Argonauta argo (each from six), and Octopus 

 vulgaris (from ten regions) ; but with regard to each of these it is probable that other species 

 have been recorded under the names of the better known ones. This is more especially 

 likely in the last instance, for the specific name vulgaris seems to impress certain 

 minds with the idea that the commonest form in all regions must be referable to it. 



The genus Sepia, in contradistinction to Octopus and Loligo which are cosmopolitan, 

 presents us with a very interesting case of wide but yet definitely limited distribution. 

 The different distributional regions contain the following numbers of species : ^ — 



I. Scandinavian, 







1 



X. Japanese, . 



. 9 



II. New England, 











XI. Australian, 



. 9 



III. West Indian, 







1 



Xir. New Zealand, . 



. 1 



IV. Lusitanian, 







5 



XIII. Pacific Insular, . 



. 1 



V. Mediterranean, 







5 



XIV. Californian, 



. 



VI. West African, 







4 



XV. Peruvian, . 



. 



VII. Soiitli African, 







5 



XVI. Patagonian, 



. 



VIII. Eed Sea, . 







.5 



XVII. Arctic, 



. 



IX. Indo-Malayan, . 







19 







From this summary it appears, in the first place, that the whole American continent 

 is devoid of any species of this genus, and that from the islands only one species 

 has been recorded and that a very doubtful one {Sepia antillarum, d'Orb.). The 

 opposite hemisphere, however, is just as rich in species as this one is poor, and the 

 greatest abundance is seen to be in the Indo-Malayan region, from which no less than 

 nineteen forms have been recorded, while the remaining districts seem to contain fewer 

 tjrpes pretty nearly in proportion as they are removed from this centre • thus Japan and 

 Australia each have nine ; the Eed Sea, South Africa and the Mediterranean each five, 

 while the Scandinavian region has only one. The conclusion is most forcibly suggested 

 that this genus was first developed in this part of the world and has gradually spread. 

 Sepia antillarum being as it were a pioneer leading the way to the occupation of the 

 Western Hemisphere. 



An interesting correspondence has often been remarked between the Scandinavian 

 and New England regions ; Verrill has called attention to it as regards the MoUusca as 

 a whole, and I have elsewhere given a comparison between the Ophiuroidea from 

 the two sides of the Atlantic. ^ As regards the Cephalopoda the- resemblance between 

 the two faunas is not striking, especially at first sight, only Octopus piscatorum and 

 Octopus arcticus being actually common to the two ; but it must be remembered that 

 several of the species of Eossia resemble each other closely {e.g., Rossia glaucopis of the 

 European, and Rossia hyatti of the American waters), while there is no doubt that Rlex 

 illecehrosus and lllex coindetii are very nearly allied to each other. This resemblance 



1 Species of the genus Sepiella are here included. ^ p,.oc. Roy. Soc. Edin., vol. xii. p. 727, 1884. 



