EXPLANATION OF PLATE XXXI. 

 ODOCOILEUS SINALO^; Allen. 



Figures 1-8 and ia-8a, J nat. size; Figs. 9-13 and 90-130, nat. size. 



Plates XXXI-XXXIII illustrate the development, and also individual 

 variation in size and form, of the antlers, from the first year to old age. 



Plate XXXI, Figs, i, 10-4, 40, dorsal view of four skulls of males less than 

 one year old (8 to n months); Figs. 5, 50-8, 8a, same view of four skulls of 

 animals in their second year (18 to about 22 months old); Figs. 9 and 90, skull 

 of male in 3d year; Figs. 10-130, sets of antlers of animals in 3d year; Plates 

 XXXII and XXXIII, antlers of animals of 4th year and older. 



FIG. i. No. 24543, Escuinapa, Sinaloa, Feb. 19, 1904; about 8 months 

 old. Dentition: dp 1 - 3 , m 1 ; m 2 just cutting the gum. Right frontal process 

 broken. J nat. size. 



FIG. 2. No. 25777, La Cienega, Jalisco, April 16, 1905; about 10 months 

 old. Dentition: dp 1 - 3 , m 1 ; m 2 just coming into use. \ nat. size. 



FIG. 3. No. 25780, La Laja, Jalisco, May 19, 1905; about n months old. 

 Dentition: dp 1 - 3 , m 1 - 2 , the last (m 2 ) already functionally developed. J nat. 

 size. 



FIG. 4. No. 26003, Volcan de Fuego, July 27, 1905; about 12 months old. 

 Dentition: dp 1 - 3 , m 1 - 2 , both molars functionally developed. J nat. size. 



FIG. 5. No. 25779, Wakenakili Mts., Jalisco, May 6, 1905; about 22 months 

 old. Dentition: dp 1 - 3 , m 1 - 3 ; m 3 fully functional. First antlers, the left one 

 already shed. nat. size. 



FIG. 6. No. 23885, Escuinapa, Sinaloa, Jan. 22, 1904; about 18 months 

 old. Dentition: dp 1 - 3 , m 1 - 3 , the last molar fully functional. nat. size. 



FIG. 7. No. 23887, Escuinapa, Sinaloa, Jan. 22, 1904; about 18 months old. 

 Dentition: dp 1 - 3 , m 1 - 3 , the last molar not fully functional. J nat. size. 



FIG. 8. No. 25779, Wakenakili Mountains, May 6, 1905; about 22 or 23 

 months old. Dentition: dp 1 - 3 already shed; n^-m 3 in full use; p 2 - 3 through 

 the gum but not functional; p 1 just breaking the gum. The right antler shows 

 as a small spike; the left one had already been shed. J nat. size. 



FIGS. 9-90. No. 24529, Escuinapa, Sinaloa, Feb. 7, 1905; 3d year (2 years 

 and about 8 months old). Dentition: permanent teeth strongly and perfectly 

 developed but showing no appreciable wear. Short spike antlers. nat. size. 



FIGS. 10-100. No. 25792, La Cienega, Jalisco; 3d year. Spike antlers, 

 medium size. nat. size. 



FIGS, ii-na. No. 25794, La Cienega, Jalisco, 3d year. Spike antlers, 

 medium size. nat. size. 



FIGS. 12-120. No. 25810, La Laja, Jalisco; 3d year. Large, heavy spike 

 antlers. nat. size. 



FIGS. 13-130. No. 25788, La Cienega, Jalisco; 3d year. Small, light, 

 3-tined, symmetrically branched antlers, in place of the usual spike antlers. 

 nat. size. 



