GILL] LIFE HISTORIES OF TOADFISHES 427 
To answer this we should have to go beyond the scope of this 
article. We shall only note a fact which gave occasion to put such 
a question. ‘There are fishes in which the branchial aperture is very 
little open, as in the gobies; others in which it is reduced to a 
foramen or a kind of tube which opens posteriorly as in the eels. 
Therefore it would have been more reasonable and suitable to give 
to Uranoscopus, which does not beat the opercles in the water and 
cannot beat them buried in the sand, a conformation of the branchial 
aperture nearly similar to that of the eels. And in fact, if the 
branchial aperture appeared from the beginning as it is at present, 
then that would indicate that the hand from which it proceeded was 
not very wise, as it had sought to hinder that which it had first 
established ; we refer to the skin portion which prolongs posteriorly 
the opercular valve and serves to close the branchial aperture in that 
place. We must, therefore, suppose this disposition to be the result 
of adaptation. But, it might then be asked, would it not have been 
more expedient if the branchial aperture had become restricted? 
The answer is, nature in her operations employs the most expe- 
ditious means to an end; it is easier, in fact, to enlarge the exten- 
sion of a part than to establish continuity where there is an 
interruption. 
These observations are printed here to call the attention of Amer- 
ican observers to characteristics which will not be manifested by the 
American Astroscopes. As the latter have the opercles roofed 
over above and lack the intramandibular linguiform appendage, 
their habits must necessarily differ from those of the Uranoscopes. 
Their contrasting peculiarities should be the subject of early con- 
sideration. The details will show how much representatives of 
nearly allied genera may differ in their habits as well as the morpho- 
logical characteristics which determine habits—or are the eventual 
outcome of differences of habits. 
