THE B ATRAC MIA OF NORTH AMERICA. 303 



cranial iutegameut. The species belong to the western and south- 

 western parts of the nearctic realm. They are distinguished as follows: 



a. Tympanic disk distinct; no gland on tibia. 



Interorbital width narrow, entering length of tibia four times; vomerine 

 teeth between choause. ; color generally dark, with or without pale stripes. 



S. Iiammovdii. 

 aa. Tympanic disk concealed ; a large gland on the upper side of the tibia. 



Interorbital width narrow, entering tibia three times; vomerine teeth a little 

 posterior to uares ; colors pale S. mitltipUcata. 



SPEA HAMMONDII Baird. 

 Cope, Jouru. Ac. Phila. (2), vi, 1866, p. 81. 



Scapliioims liammondii Baird, Rept. Expl. Surv., iv, Roptil., 1859, PL 28, fig. 2; Cope, 



Proceed. Ac. Phila., 1863, p. 53; Boulenger, Cat. Batr, Sal. Brit. Mus., 1882, p. 435. 

 ScapMopus homhifrons Cope, Proceed. Ac. Phila., 1863, p. 53; Boulenger, Cat. Batr. 



Sal. Brit. Mus., 1882, p. 435. 

 Spea iomhifrons Cope, Jouru. Ac. Phila. (2) vi, 1866, p. 81. 

 Spea stagnalis Cope, U. S. G. G. Surv. W. of 100th Merid., V, Zool., p. 525, PL 25, 



figs. 6-8. 

 Scaphiopus stagnalis Boulenger, Cat. Batr., Sal. Brit. Mus., 1882, p. 436. 

 Sca2}hiopus diigesii Broccbi, BulL Soc. Philom. (7), iii, 1879, p. 23, and Miss. Sci. 



Mex., Batr., p. 94, PL 9, fig. 4 ; Boulenger, Cat. Batr. Sal. Brit. Mus., 18-2, p. 436. 



This is a widely distributed and variable species, presenting such 

 diversity in some respects as to be interesting as an example of the 

 appearance of important characters in the course of descent. It is in- 

 teresting also from its habits, adapted as they are to the exigencies of 

 a dry climate, in which the opportunity for aquatic life is precarious, 

 and the metamorphosis correspondingly^ liable to modification. 



1 include three subspecies under the common head, which are defined 

 as follows : 



Generally no frontoparietal fontanelle ; head plane above; a longitudinal pale band 

 on each side of back ; larger ; skin tubercular S. h. intermontana. 



A frontoparietal fontanelle; head plane or convex above; no longitudinal light 

 bands; skin smoother ; smaller S. It. hammondil. 



A frontoparietal fontanelle ; head very convex at the interorbital region ; skin nearly 

 smooth ; colors pale ; size least S. h. bomUfrons. 



I had first placed the S. h. intermontana in the genus Scaphiopus, 

 while the two other subspecies were placed with the S. multiplicata 

 in a distinct genus, Spea, which was characterized by the presence of 

 a frontoparietal fontanelle. This character is generally constant, al- 

 though its inconstancy as a specific character is to be expected some- 

 where. The genus Spea is the seat of the failure of this generic char 

 acter to coincide with the other definitions of a species. In one of the 

 four specimens of the subspecies Intermontanus I find the fontanelle 

 present, while in three it is absent. lu a fifth specimen it is repre- 

 sented by a fissure between the frontoparietal bones. 



The S. h. homhifrons appears to be, at first examination, a well de- 

 fined species. The interorbital protuberance is a striking character. 



