TRIMERORHACHIS, A PERMIAN AMPHIBIAN 247 



be little doubt that Eosauravus, from the Coal Measures of Linton, 

 Ohio, is a real reptile; and Watson has recently figured' a femur 

 from the Lower Carboniferous of Scotland that he believes to be 

 of a true reptile, or at least of a "precocious" amphibian. I think 

 that he is right. 



Fig. I. — Skull of Trimerorhachis insignis Cope. One-half natural size; pm, 

 premaxiUa; na, nasal; p, prefrontal; pf, postfrontal; po, postorbital; it, inter- 

 temporal; pa, parietal; st, supratemporal; j, jugal; sq, squamosal; ds, dermosupra- 

 occipital; t, tabulare; I, lacrimal; m, maxilla; qj, quadra to jugal; sp, splenial; psp, 

 postsplenial; an, angular; art, articular. 



Trimerorhachis was a purely aquatic amphibian, as its mode of 

 occurrence indicates and as its structure demonstrates. The 

 characters showing aquatic adaptation are found in the anterior 

 position of the orbits and their direction upward; in the relatively 



' Geological Magazine (1914), p. 347. 



