100 BULLETIN 151, UNITED STATES NATIONAL MUSEUM 



The 15 young show a range in length from 25 to 37 mm., with an 

 average of 30.2 mm.; very small stumpy rudiments of larval tails are 

 present in four frogs, measuring 26, 27, 28, and 29 mm., respectively. 



2. The center of the throat is mottled in all but three frogs (Nos. 

 41219, 41273, 42956), where it is plain. 



3. The tibio-tarsal articulation of the adpressed hind limb reaches 

 beyond the end of the snout except in three frogs; in one of these 

 (No. 41105) it reaches to the end, while in two others (Nos. 41958, 

 42956) it onh reaches the nostril. 



As to this last-mentioned frog (No. 42956) I am not certain that 

 it should not be referred to aherdariensis for in a third feature — 

 the roundish vomers — it seems allied to that species, I have hesitated 

 to do so chiefly because other young in the same series, as well as 

 the adults, are all obviously nutti. 



A reexamination of the 192 examples of Rana nutti from Tanganyika 

 Territory *^ show that these were all correctly identified as nutti, 

 and that, while the tibio-tarsal articulation of the adpressed hind limb 

 reaches beyond the end of the snout in four-fifths of the series, in 

 the remaining fifth — principally composed of younger individuals — 

 it only reaches the nostril or end of snout. Under the heading of 

 Rana aherdariensis I have already given reasons for now considering 

 that species distinct. The separating of specimens being by no 

 means easy it might be well to summarize these conclusions in the 

 form of a simple key. Apart from the vomers which are rounded in 

 aherdariensis and elongate in nutti the differences may be summarized 

 thus: 



MALES 



In specimens over 46 mm. the center of throat is always immaculate; laterally 

 a blue-gray patch over folds of vocal pouches; a band of minute spinosities 

 across the belly in breeding season; the tibio-tarsal articulation does not usu- 

 ally reach beyond the eiKl of the snout (range from eye to bej'ond end of 

 the snout) aherdariensis. 



In specimens over 35 mm. the center of throat is usually mottled (quite often 

 not); no blue-gray patch or lateral vocal pouches; no band of minute spinosities 

 across the belly in the breeding season; the tibio-tarsal articulation almost 

 always reaches well beyond the end of the snout (range from end of snout 

 to beyond) nutti. 



FEMALES 



Center of throat mottled or plain; the tibio-tarsal articulation rarely reaches 

 beyond the nostril (range from eye to end of snout) aherdariensis. 



Center of throat more often mottled than plain; the tibio-tarsal articulation 

 usually reaches well beyond the end of the snout (range from nostril to beyond 

 end of snout) nutti. 



" Mem. Mus. Comp. Zool., vol. 50, p. 194. 



