56 MAMMALIAN DE.^CENT. [Lect. IT. 



After writing the above, I received from Professor Simon H. Gage, 

 E.S., of Cornell University, Itliaca, N.Y., a most important com- 

 munication on the respiration of certain fresh-water Tortoises. The 

 information thus given covers just a page and a half, and yet it is of 

 more value to the biologist than some bulky volumes that one 

 could name. I shall insert it, bodily. Let the facts there disclosed 

 be but fairly considered, and the difficulty of suj)posing a gradual 

 melting down of the distinctions between the Amphiljia and Reptilia 

 will be at an end. 



The lining of the pliarjjmr, or upper part of the gullet, is the 

 l^roper normal respiratory organ of any creature possessed of a 

 notocliord^ or primary spinal axis. All the various s^Dccialisations 

 that may be found in Ascidians (Sea-squids), Ampliioxus (the 

 Lancelet), and in all the Vertehrata, are of secondary importance to 

 the embryologist. The peculiar structure and functions of the 

 pharynx described l)y Professor Gage may be due to degradation 

 or relapsp, but if so, it only proves that the aquatic ivas once 

 the mode of respiration in the stock from which these Tortoises 

 sprang. 



"Pharyngeal Respiration in the Soft-Shelled Turtle {Aspidonedes 

 spinifer). By Simon H. Gage of Ithaca, X.Y. 



"During the last twenty-five years the mechanism of respiration 

 in the Chelonia has been investigated with considerable thoroughness, 

 both in this country and in Europe ; and at j^resent the Chelonian 

 form of respiration is considered to be comparable Avith that of the 

 mammal rather than with that of the frog, as formerly supposed. 

 AVliile, however, the mechanism of respiration has been quite fully 

 investigated, there has been, so far as I am aware, but one who 

 has considered the organs of respiration in the different groups of 

 turtles. 



" Professor Agassiz, in Part II. of the Contrilidions to North 

 American Zoology (p. 284), states that the lung capacity of the 

 soft-shelled turtle is far less in proportion to its body-weight than 

 is that of the land turtles. He also states, in considering this fact, 

 that the skin on tlie ventral side of the body, from its rich network 



