ON ZGEAN INVERTEBRATA. Ma 
The consideration of the representation in space forms an important ele- 
ment in our comparisons between the faunas of distinct seas in the same or re- 
presentative parallels. The analogies between species in the northern and 
southern, the eastern and western hemispheres, are instances. But there is 
another application of it which I would make here. The preceding tables 
and list afford indications of a very interesting law of marine distribution, 
probable @ priori, but hitherto unproved. The assemblage of cosmopolitan 
species at the water's edge, the abundance of peculiar climatal forms in the 
highest zone, where Celtic species are scarce, the increase in the number of 
the latter as we descend, and when they again diminish the representation of 
northern forms in the lower regions, and the abundance of remains of Ptero- 
poda in the lowest, with the general aspect of the associations of species in 
all, are facts which fairly lead to an inference that parallels in latitude are 
equivalent to regions in depth, correspondent to that law in terrestrial distri- 
bution which holds that parallels in latitude are representative of regions of 
elevation. In each case the analogy is maintained, not by identical species 
only, but mainly by representative forms; and accordingly, although we find 
fewer northern species in the faunas of the lower zones, the number of forms 
representative of northern species is so great as to give them a much more 
boreal or subboreal character than is presented by those regions where iden- 
tical forms are more abundant. 
The consideration of the law of representation in time illustrates importantly 
the history of the very few species hitherto known only as distinct, which 
were discovered during the course of these researches in the gean. They are 
. either such species as have had their maxima during the tertiary era and are 
now fast approaching extinction, or such as had their infancy in the latest 
preadamic formations and are now attaining their maxima. Of the first, 
Nassa substriaia, hitherto regarded as a characteristic tertiary shell, is an in- 
stance. Abounding in all the latest tertiaries of the Archipelago and of 
Europe generally, apparently gregarious, half a dozen straggling individuals 
were all that occurred in above 150 dredgings throughout the gean, those 
too in a region below their usual habitation when the species was in its prime. 
Of the second, Neera costulata is an example; a few specimens of which 
only had been derived from tertiary deposits. 
The result of the examination of the Aigean fauna does not hold out much 
prospect of the discovery of any more important extinct forms in a living 
state. The very few which I have been so fortunate as to discover are not 
such as materially to disturb the calculations of the geologist, especially if he 
takes into consideration the relations of each species to others and to its own 
maximum and minimum in time and geographic distribution. To those who 
have looked forward to the finding of lost forms in the greater depths of the 
sea, the catalogues I here present to the Association must be unsatisfactory ; 
for though two or three such have occurred, the majority of species in the 
great depths are either described existing forms, or altogether new. The zero 
of animal life in depth has been too nearly approached to hold out further 
hopes. The indefatigable researches of Captain Graves and his officers have 
supplied me, since my return, with a mass of new data from all depths and 
from many new localities; but the result of their examination has been to 
confirm the calculations I had made from my own observations, and to lead 
to the pleasing hope that the researches embodied in this report will form a 
safe base-line for future investigations in the same department of philosophic 
zoology. 
Were the bottom of the /Egean sea, with its present inhabitants, to be ele- 
vated and converted into dry land, or even that sea be filled up by a long 
