FISHES OF LAKE SUPERIOR. 261 



the successive creations all this herpetological relationship, and were, 

 at last, endowed with characters which contrast as much, when com- 

 pared with those of reptiles, as they agreed closely in the beginning. 

 Lepidosteus alone reminds us, in our time, of these old-fashioned 

 characters of the class of fishes, as it was in former days. 



An opportunity afforded me by John Edward Gray, Esq., of the 

 British Museum, of examining a specimen of this genus, preserved 

 in alcohol, furnished another evidence that the reptilian character 

 of Lepidosteus was not only shown in its solid parts, but was even 

 exemplified in the peculiar structure of its respiratory apparatus and 

 its cellular air bladder, as I have pointed out in the Proceedings of 

 the Zoological Society of London.* 



One step further was made during this excursion, when, at Niag- 

 ara, a living specimen of Lepidosteus was caught for me, and to my 

 great delight, as well as to my utter astonishment, I saw this fish 

 moving its head upon the neck freely, right and left and upwards, 

 as a Saurian, and as no other fish in creation does. 



This reptilian character of the older fishes is not the only striking 

 character which distinguishes them. Investigations into the em- 

 bryonic growth of recent fishes have led me to the discovery that 

 the changes which they undergo agree, in many respects, in a 

 very remarkable manner, with the differences which we notice be- 

 tween the fossils of different ages ; so much so, that the peculiar 

 form of the vertebral column, and especially its odd termination hi 

 very young embryos, where the upper lobe of the caudal fin is pro- 

 longed beyond the lower lobe, and forms an unequal, unsymmetrical 

 appendage upwards and backwards, agrees precisely with the form 

 of the tail of the bony fishes of the oldest geological deposits ; so 

 that these ancient fishes may be said to have embryonic peculiarities 

 in addition to their reptilian character. This fact, so simple in itself, 

 and apparently so natural, is of the utmost importance in the history 

 of animal life. It has gradually led me to more extensive views, and 

 to the conviction that embryonic investigations might throw as much 

 light upon the successive development of the animal kingdom during 

 the successive geological periods, as upon the physiological develop- 



Proceed. Zool. Soc. of London, Vol. II. page 119. 



