324 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



district. But three of tlie genera found in tlie latter are known to 

 exist in any other. The poverty of the Chilian district is marked, 

 while West Indian species are nearly all of one genus, the Scytopls 

 noted being the 8. ruber of Surinam, which occurs in Trinidad. None 

 of the species ever pass these bounds, with the last-mentioned exception, 

 and those of Scyto])is venulosus, Hypsiboas albomarginatus and xerophyl- 

 lum, which occur in the eastern and adjoining j)Oi'tion of the Mexican 

 region. Our knowledge of this subject is, however, very incomplete. 



In the species of Hylidae coloration may be distributed into two 

 regions; the first including that which is exposed to the light when the 

 animal is crouched, with the limbs all flexed and close pressed to the 

 sides, the hands and feet concealed more or less under the body ; and 

 the second embraces what is thus hidden from the light, especially the 

 portions in actual contact in flexure. Any marked difference in color 

 of the different surfaces will usually be found to have reference to this 

 division into regions, generally very dissimilar in appearance. This 

 is well seen in Hyla andersonii, caroUnensis, and in Phyllomedusa and 

 Agalychnis. Fpr convenience of reference, I here, as in other genera 

 of Batrachia Salientia, term the portions of the body and limbs which 

 are exposed to the light external 5 those concealed in the flexure, in- 

 ternal. 



AORIS Dumeril and Bibron. 



Erp. G611., VIII, 506; Giinthp, Cat. Batr. Sal. Brit. Mus., i ed., 1856, p. 

 71; Cope, Nat. Hist. Kev., ib65, p. 110; Cope, Journ. Ac. Pliiia. (2), 

 VI, 1866, 86 ; Boulenger, Cat. Batr. Sal. Brit. Mus., 1882, 11 ecL, p. 336. 



But one species of this genus Is known, and it is found throughout 

 the greater part of the North American realm. It is quite possible that 

 it may become necessary at some future time to unite this genus with 



Hyla. 



ACEIS GRYLLUS Le Coute. * 



Dum. & Bibr. Erp. G6u., viii, 507; Le Coute, Proceed. Ac. Phila., 1855, 

 28; Boulenger, Cat. Batr. Sal. Brit. Mus., 1882, 336. 

 Bana gryllus Le Conte, Auu. Lyceum New York, i 1825, p. 282; Harlau, Med. Phys. 



Res., p. 104. 

 Bana dorsalis Harlau, I. c, p. 105. 

 Hylodes (jrijUus Holbr., N. Amer. Herp., PI. 33. 



Head moderate, length to canthus oris equal breadth at same point. 

 Muzzle narrowed, produced ; profile projecting or nearly perpendicular. 

 Canthus rostral is weak, approximate 5 external nostril little nearer edge 

 of lip than to orbit. Vertex plane; diameter of orbit greater than iu- 

 terorbital breadth, three times in length from end of nauzzle to posterior 

 border of t.ympanic membrane. Latter indistinct; partially obscured 

 by a fold one-fifth the size of the orbit. Skin of head and body above 

 with rather distant tubercles, of which some on the scapular regions are 

 more or less i)liciform. No areolation on thoracic and gular region. 

 A series of small tubercles on the outer border of the tarsus ; two small 

 metatarsal tubercles. Articular tubercles of the phalanges very small. 

 ' * Plate 73, fig. 29. ' 



