EXPLANATION OF PLATE XX. 

 TAYASSU ANGULATUM SONORIENSE (Mearns). 



FIG. i (upper figure). No. 24593, a d- d\ Escuinapa, Sinaloa. Ventral 

 view of middle region of a normal skull. \ nat. size. 



FIG. 2 (lower figure). No. 24586, ad. $ , Escuinapa, Sinaloa. Ventral 

 view of middle region of skull, showing pathological conditions. \ nat. size. 



Note the tubular expansion of the inferior orbitosphenoid-lachrymal region, 

 and the greatly inflated maxillary portion of the zygoma. This condition is 

 present in rather more than 50% of the Escuinapa series, and in about the same 

 proportion of skulls from other localities in Mexico, Texas, and Arizona; in 

 80% of skulls (large series of each species) of T. torvum and T. tajacu from, 

 respectively, Colombia and Brazil, and in nearly 100% of a large series of 

 skulls of T. pecari from the Santa Marta district of Colombia. 



