124 BULLETIN 160, UNITED STATES NATIONAL MUSEUM 



A taxonomist should act as an impartial judge in matters relating to 

 the validity of species, for it is his business to ascertain how many 

 actually exist and, having done so, to designate the characters by 

 which they may be recognized. Unfortunately, the lack of a uniform 

 yardstick for measurement of distinctness makes the recognition of 

 species a matter of interpretation, since different sets of characters 

 must unavoidably be used in the discrimination of species in unrelated 

 and occasionally in related genera. 



Specimens collected half a century or more ago are generally so 

 poorly preserved that any precise determination of their structural 

 peculiarities is out of the question. Freshly preserved specimens 

 would be much better to work with than some of the types of Mexi- 

 can species of Syrrhophus described by Cope. A satisfactory eluci- 

 dation of the Mexican species of Syrrhophus will necessarily await 

 the accumulation of an adequate series of well-preserved or of living 

 individuals, preferably topotypes. For the present the toothless 

 eleutherodactylids to which names have been applied are listed 

 merely as nominal species without regard to their possible relation- 

 ships, since in most instances they are known solely from the material 

 available to the original describer. 



According to H. W. Parker ^' the large eggs of Syrrhophus suggest 

 a shortened life history. 



KEY TO MEXICAN SPECIES OP SYRRHOPHUS 



1. Tympanum very small, one-third or at most less than one-half 



the diameter of the eye 2 



Tympanum larger, one-half to two-thirds the diameter of the 



eye 



2. Smooth skin on hinder half of abdomen; tympanic membrane 



one-third the diameter of the eye; canthal region rounded, 

 with no discernible ridge; loreal region subvertical; muzzle 

 broadly acuminate and obtuse; head flat above, the maxi- 

 mum width of upper eyelid two-thirds the width of interor- 

 bital region; nares lateral and terminal, and their distance 

 from eye less than one-half the diameter of the latter; tongue 

 subpyriform; skin of upperparts, sides, throat, chest, and 

 belly smooth; underside of thighs coarsely granulated; fingers 

 free, without any vestige of membrane at base; first finger 

 shorter than second; large subarticular or supernumerary tuber- 

 cles at ends of metapodials of fingers; apical disks of fingers 

 and toes slightly wider than corresponding digit, but not 

 especially enlarged, truncated at extremity, and flattened; 

 a large palmar tubercle; toes with slight vestige of web at 

 base; free portion of fourth toe more than twice the length of 

 free portion of fifth; small subarticular or supernumerary 

 tubercles extended backward on inferior surfaces of metatar- 

 sals; inner metatarsal tubercle larger than outer; the hind limb 

 being carried forward along the body, the tibio-tarsal joint 

 reaches about the middle of the eye; the hind limbs being 



« Parker, H. W., Ann. and Mag. Nat. Hist., ser. 9, vol. 20, no. 118, p. 452, Oct., 1927. 



3 



