ON THE CONCORDANCE OE MOLLUSCA. 555 



Judging from an examination of the Mollusca procured by the 

 Challenger expedition, I am not disposed to admit the uniformity of the 

 Mollusca which inhabit the deep-sea areas of the Atlantic and Pacific 

 oceans throughout the globe. 



I hope that these notes, although short and imperfect, may be the 

 means of eliciting the opinions of those naturalists who take an interest 

 in the important question of the extent and mode of distribution of 

 marine animals. I regret exceedingly that other engagements will pre- 

 vent my personally taking part in the discussion. 



P.S. — Since writing the above I have received, through the kindness 

 of Professor Verrill, his ' Second Catalogue of Mollusca recently added to 

 the Fauna of the New England Coast, and the adjacent parts of the 

 Atlantic, consisting mostly of deep-sea species, with notes on others pre- 

 viously recorded.' This catalogue was published in the ' Transactions 

 of the Connecticut Academy ' for April, May and June, 1884. Twenty- 

 seven European species (most of which were described by me) have now 

 been recognised by Verrill as also inhabiting the American side of the 

 North Atlantic, and probably some more of the species in his Catalogue, 

 as well as many of those in my own papers, may have to be ultimately 

 placed in the same category. 



On the Characteristics of the North American Flora. 

 By Professor Asa Gray. 



[A communication ordered by the General Committee to be printed w emtenso among 



the Reports.] 



When the British Association, with much painstaking, honours and grati- 

 fies the cultivators of science on this side of the ocean by meeting on 

 American soil, it is but seemly that a corresponding member for the third 

 of a centuiy should endeavour to manifest his interest in the occasion and 

 to render some service, if he can, to his fellow-naturalists in Section D. 

 I would attempt to do so by pointing out, in a general way, some of the 

 characteristic features of the vegetation of the country which they have 

 come to visit, — a country of ' magnificent distances,' but of which some 

 vistas may be had by those who can use the facilities which are offered 

 for enjoying them. Even to those who cannot command the time for dis- 

 tant excursions, and to some who may know little or nothing of botany, 

 the sketch which I offer may not be altogether uninteresting. But I 

 naturally address myself to the botanists of the Association, to those who, 

 having crossed the wide Atlantic, are now invited to proceed westward 

 over an almost equal breadth of land ; some, indeed, have already 

 journeyed to the Pacific coast, and have returned ; and not a few, it is 

 hoped, may accept the invitation to Philadelphia, where a warm wel- 

 come awaits them — warmth of hospitality, rather than of summer tem- 

 perature, let us hope ; but Philadelphia is proverbial for both. There 

 opportunities may be afforded for a passing acquaintance with the botany 

 of the Atlantic border of the United States, in company with the botanists 

 of the American Association, who are expected to muster in full force. 



What may be asked of me, then, is to portray certain outlines of the 

 vegetation of the United States and the Canadian Dominion, as con- 



