38 BIOLOGICAL SOCIETY OF WASHINGTON. 



ences. Most of the species hitherto found, it is true, have been 

 obtained only about one locality, but it must be remembered tliat 

 comparatively few individuals have been found, and their acquisi- 

 tion is often due to happy accidents rather than special collecting. 

 On general principles, we are prepared to expect such a wide 

 range. In the abyssal depths, which these animals inhabit, the 

 conditions are perfectly uniform, and have so remained practically 

 for geological ages, and it is, therefore, quite natural that among 

 such forms we should find representatives of types that long ago 

 disappeared from other parts of the globe. . 



It will be observed that I have given for the several realms names 

 with a uniform termination, employing the suffix gcea for the inland 

 and a/i'a for the marine ones ; the former has been frequently used 

 before ; the latter is a transliteration of the Ionic Greek u?.ia, (an 

 assembly or gathering,) and is selected on account of the flavor or 

 reminiscence it involves of the salt of the sea, or the sea 

 itself.* I think myself that such a system of nomenclature will be 

 convenient on accout of dissociating our ideas of geographical 

 realms from precise geographical regions, and also emphasizing the 

 contrast between the inland and marine faunas. Whether they 

 shall be adopted or not, however, must be left for individual prefer- 

 ence. 



Permit me now to indicate certain desiderata, and how our 

 knowledge of zoogeography may be extended. Full catalogues of 

 all the animals found at specific points will be especially useful, but 

 to insure their usefulness, data should be given respecting their sea- 

 sonal or permanent sojourn, their abundance, the depths at which 

 they live, and the temperature of the water at various seasons. 

 Great caution should be exercised, too, in admitting forms which 

 may be simply adventitious wanderers, for the cac(xthes acqiiisi- 

 fionis may impose serious obstacles to the proper appreciation of 

 zoogeographical principles. Of course, I do not mean that the 



* Compare (tu'M).)J.Zo) (from ,j,'rj and dki'^M^ to a'^semWe or, radically, come 

 tocrether around the salt. 



