182 THE AMERICAN NATURALIST. [VOL XXXII. 
tinues as follows: “ My object was only to utilize certain struc- 
tural characters which frequently recur among fossil forms, and 
which might therefore enable me to determine remains hitherto 
considered of little value.” } 
Lastly, the Poissons Fossiles is notable for still constituting 
the most valuable repository of information we have on fossil 
fishes. In it are enumerated more than one thousand species, 
the greater part of which are accurately described and magnifi- 
cently illustrated; and it is worth recording that the first suc- 
cessful application of chromolithography was in the execution 
of these plates. The fidelity of the drawings to nature and 
the minuteness of the accompanying descriptions have never 
ceased to challenge wonder and admiration. 
Passing now for a moment to Agassiz’s supplementary 
volume on the Fishes of the Old Red Sandstone, one cannot but 
feel amazement at the accuracy, cleverness, and originality of 
the author as displayed throughout this truly wonderful work. 
Greater difficulties were encountered in the way of studying 
the remains, which were scanty at best and imperfectly pre- 
served; and more intricate problems presented themselves 
respecting the anatomy and homology of parts than any he had 
met with in the preparation of his larger work. True, the dis- 
covery of the Ludlow and Cromarty faunas was not a matter of 
long standing, but it had already engaged the attention of the 
most eminent British geologists and paleontologists, who were 
one and all confounded over the problematical organisms. But 
whether as a result of his training or intuition, or both, Agassiz 
had no hesitation in declaring, the moment he examined one of 
Hugh Miller’s drawings and description of Pterichthys, that the 
creature was a chordate, and belonged to the class of fishes. 
His astonishment, however, on first seeing the actual fossils, is 
well told by himself in the preface to his monograph, as 
follows: 
I can never forget the impression produced upon me by the sight of these 
creatures, furnished with appendages resembling wings, yet belonging, as I 
had satisfied myself, to the class of fishes,... It is impossible to see aught 
more bizarre in all creation than the Pterichthyean genus; the same aston- 
E. C. Agassiz, Joc. cit., p. 203. 
