344 M. Agassiz on Fossil Fishes. 



they exist at all, are true locomotive organs ; they cannot, 

 however, elevate the whole mass of the body, which is dragged, 

 rather than carried, by the feet. These animals are evidently 

 superior to fishes in the development of the organs of the 

 senses and intellectual faculties; more varied relations be- 

 tween individuals of the same species are accordingly found 

 among them. In birds, which come next in order, we observe 

 a very remarkable development. Without attempting to de- 

 monstrate the indisputable superiority of their organization 

 over that of the two preceding classes, I shall insist only on 

 this single fact, that their bodies can be completely raised 

 from the ground by means of their locomotive members, 

 which present, in their disengagement from the body, the 

 most striking contrast with the locomotive appendages of 

 fishes and reptiles. We constantly find in birds two kinds 

 of locomotive members, wings for flight, and feet for walking 

 or swimming ; and, what is curious, when they rest, these 

 animals support themselves only on their posterior limbs, the 

 body and head inclined forward and upwards. Among the 

 mammifera, we find, for the first time, an organization in 

 which all the limbs harmonize — all of them maintaining the 

 body in an elevated position. We need not be surprised, 

 however, to find, in this class, types as varied as the Cetacea, 

 Quadrupeds properly so called, the Cheiroptera, and the quad- 

 rumana ; for, after a development as eccentric as that of birds, 

 what can be more natural than to find the mammifera repro- 

 duce, in their sphere, forms which recall inferior types, as if 

 it were definitively to overcome the relations which connect 

 animals with the soil, before attaining to the noble gait and 

 free movements which characterise man, and which permit 

 him to elevate his face towards his Creator — to contemplate 

 the entire universe — ^to perceive the laws which regulate it, 

 — and to prostrate himself with gratitude and love before 

 Him to whom he is indebted for such marvellous preroga- 

 tives." 



The class of fishes, considered in itself, has likewise under- 

 gone numerous modifications during the series of geological 

 ages, from the period of the transition formations down to our 

 own times. Here, as in all the other classes of the animal 



