CROCODILES AND LUNG-FISHES 127 



fundamental principles. A concrete instance of "not 

 seeing the wood for the trees." 



The three following scientific memoirs represent part 

 of the work done during 1875, though the two last were 

 not published till the following year : — 



1. "On Stagonolepis Robertsoni, and on the Evolu- 

 tion of the Crocodilia" (Q. J. Geol. Soc, xxxi, 1875, 

 pp. 423-38. Sci. Mem., iv, vii, p. 66). — This famous 

 memoir propounds an evolutionary classification of croco- 

 dilian reptiles, including the ancient extinct type named. 

 The hinder openings of the nasal cavities are placed far 

 back in the throat in recent crocodiles, and so disposed 

 that the mouth can be kept open under water without 

 danger of suffocation, an obvious adaptation to the aquatic 

 habit. The way in which this arrangement has gradually 

 evolved is here set forth. 



2. " Contributions to Morphology. Ichthyopsida. No. 

 I. On Ceratodus Forsteri, with Observations on the 

 Classification of Fishes" (Proc. Zool. Soc, 1876, pp. 

 24-59. Received January 4, 1875. Sci. Mem., iv, 

 VIII, p. 84). — The form in question is the Australian 

 Lung-fish, one of the few surviving members of a once 

 widely distributed and dominant marine group, which 

 have been saved from extinction by taking to a life in 

 fresh water, where the struggle for existence is less 

 severe. The classificatory part of the memoir, largely 

 based on the characters of the skull and fins, is distinctly 

 of epoch-making character, and has had to be reckoned 

 with in all subsequent attempts to place the systematics 

 of fishes on a sound footing. 



3. " On the Position of the Anterior Nasal Apertures 

 in Lepidosiren " (op. cit., pp. 180-1 , Received January 7. 

 1876. Sci. Mem., iv, ix, p. 125). — This is a note on 

 the South American Lung-fish. . 



