THE PRE-ADAMITE EAKTH. 



branchia (gills), include nearly all the Mollusca ; among the 

 Annulata they include the Crustacea, the Annalids, and the 

 Cirrhipeds ; and among the Vertehrata, all the fishes. "We find 

 all these represented in the Palaeozoic age ; and, on ascending 

 from age to age, no modification of the respiratory apparatus is 

 manifested. The living Species which have branchial respiration 

 belong to the same class as those which exercised like functions 

 during the Palaeozoic age. 



544. All these circumstances lead, therefore, to the conclusion 

 that the external conditions in which animals exist have undergone 

 no essential change since the Palaeozoic age, inasmuch as the organs 

 of respiration have remained the same, a conclusion which is still 

 further confirmed when, descending from the orders, the genera 

 are examined. 



545. In fine, to the question whether the marine animals have un- 

 dergone any change in their structure since the first animalisation 

 of the globe, or if they have greatly improved in their organisation, 

 we may answer without hesitation by an absolute negative ; for 

 these primitive genera, or those most closely allied to them, which 

 still represent them on the earth, prove that they had from the 

 first the organic characters which they still preserve that they 

 have undergone no gradual improvement in organisation that 

 the medium in which they lived at the earliest epoch of the 

 creation was the same as at present that, therefore, no great 

 change has taken place as to the conditions of vitality of these 

 beings, and that the seas in which they then existed are essentially 

 similar to those which they now inhabit. 



546. All the terrestrial animals, whether of land or water, which 

 breathe otherwise then by branchia, belong to the two classes 

 which breathe either by trachea or lungs. 



Less perfect than pulmonary, tracheal respiration is peculiar to 

 the class of insects and some Arachnida. -We find this function 

 perfectly represented in the animals of the Palaeozoic epoch. As 

 has been already stated, Coleoptera, Orthoptera, and Neuroptera, 

 all of tracheal respiration, have been discovered in the Palaeozoic 

 strata. As these insects belong to the same or analogous genera with 

 those which now exist, we must assume that they were endowed 

 with the same respiratory organs. "We arrive, therefore, at the 

 conclusion, as well for terrestrial animals which breathe by 

 trachea, as for marine animals, that the respiratory organs have not 

 undergone any progressive improvement, and that this class in 

 the cradle of nature was what it still is ; in fine, that the medium 

 of its terrestrial existence has always been the same, since the 

 first animalisation of the globe to the present time. 



547. Pulmonary respiration prevails in three of the principal 

 150 



