130 ]\Ir. G. A. Boulenger on neiv 



Inition of marine animals lias features wliicli divero-e from 

 those which cliaracterize the distribution of land-animals — 

 accordino" to the views now prevalent ; and, further, that 

 the absence of impassable barriers does not, of necessity, lead 

 to a cosmopolitan habit in those which can avail themselves 

 o£ the opportunity. In the case of land-animals much 

 weio;ht has been placed on this check to migration, so that 

 it is a prominent feature in the literature of the subject. 

 Further, the conditions in the ocean tend to the permanence 

 of the various types, which, with their wide distribution, 

 varied sites, and uniform medium, have much to favour them 

 in the struggle for existence. The vast or cosmopolitan 

 distribution of many forms is thus conspicuous. 



Again, in the present state of knowledge, the division of 

 the ocean into regions characterized by special faunistic 

 features can with difficulty, to say the least, meet with 

 support from all the groups of marine animals. 



This preliminary survey of the subject, moreover, is in- 

 teresting insofar as it discloses no serious obstacle to the 

 introduction of European food-fishes, shell-fishes, crabs, and 

 other forms to various parts of the world — especially those of 

 primary importance to man. If, for instance, the same or a 

 closely allied shell-fish or annelid can live and flourish equally 

 in the waters of Britain and those of the Cape, there is pro- 

 bably no insuperable barrier to the transference of a valuable 

 food-fish from the one to the other. The recent transmission 

 of adult plaice from Scotland to Australia has already met 

 with success, and the same experiment may soon be carried 

 out at the Cape. 



Though at present, broadly speaking, no definite plan of 

 distribution amongst the families of oceanic forms is dis- 

 cernible — very few families being monopolized by one region 

 to the exclusion of the others, — future investigators may 

 enable such a plan to be outlined ; yet the number of cosmo- 

 politan forms, and of others which range almost as widely, 

 will always give a tone to the picture of the sea in contrast 

 with that of the land. 



XIV. — Descriptions of new Frogs and Snakes from Yunnan. 

 By G. A. Boulenger, F.R.S. 



In a recent number of these 'Annals' * I described a new 

 gecko, GeJiT/ra T/unnanensis, obtained at Yunnan Fu (altitude 



* Vol. xii. 1903, p. 429. 



