664 MR. E. R. ALSTON ON NEOTROPICAL SQUIRRELS. [June 18, 



the back, as in the last phase, while the rufous-bellied phases lead 

 us directly back into the rigidus form. 



5. The melania type. Upper and lower parts uniform glossy dark 

 brown, often with irregular patches of paler brown. This is a very 

 peculiar phase, and I have not yet seen any direct intergradation with 

 the other varieties ; but uniformity of coloration is so abnormal 

 among the Squirrels, that it seems impossible to doubt that Mr. Allen 

 is right in regarding it as a melanism. The colour is exactly similar 

 to that of the white-bellied dorsalis varieties, in which also the paler 

 apparently faded patches are sometimes seen. It appears to be much 

 rarer than any of the other forms described. 



With regard to the synonymy, I may observe that I have been 

 able to examine the types of all the "species" here united, except- 

 ing that of <S. hypopyrrhus, which, however, has been well described 

 by Wagler and Wagner ; it appears to be a dark variety without 

 the usual wash of white on the tail. That of S. nigrescens only 

 differs in having the fur of the lower parts ringed like that of the 

 back ; it agrees well with specimens in the Paris and Berlin Museums. 

 8. collicei and S. adolphei are synonyms for the white-bellied form 

 above described, from which I am also unable to distinguish S. 

 richardsoni of Gray (not of Bach man), on which both S. boothice and 

 S. fuscovariegatus were founded. S. variegatoides, S. griseocauda- 

 tus, S. pyladei, and S. oculatus are all intermediate links with more 

 or less fulvous lower parts, leading to the phase with a red or red 

 and white belly, on which the names S. intermedins, S. rigidus, 

 and Macroxus nicoyanus have been bestowed. 



Of the geographical distribution of the various races we can only 

 judge from the comparatively few specimens of which the exact 

 localities have been noted. The hypopyrrhus phase appears to be 

 the most northern, the collicei to obtain principally along the Pacifie 

 slopes, and the dorsalis to be the most southern. Each, however, 

 appears to be found along with others in some part. Thus, I have 

 seen specimens of hypopyrrhus type from Mexico, Honduras, and 

 Guatemala, of rigidus from Guatemala, Nicaragua, and Costa Rica, 

 of dorsalis from Nicaragua, Costa Rica, Veragua, and Panama, and 

 of collicei from the west coast of Mexico and Guatemala, Nicaragua, 

 and Costa Rica. The only localities which I know for S. melania 

 are Nicaragua and Veragua. 



VI. SCIUKUS STRAMINEUS. 



Sciurus strumineus, Eydoux & Souleyet, Voy. de 'La Bonite,' 

 Zool. i. p. 37, Atlas, pi. ix. (1841). 



* Sciurus nebouxii, Is. Geoffroy, Voy. de 'La Venus,' Zool. p. 163, 

 Atlas, pi. xii. (1855). 



*Macroms fraseri, Gray, Ann. & Mag. Nat. Hist. ser. 3, xx. 

 p. 430 (1867). 



(Sciurus hypopyrrhus, Allen, Mon. N.-Am. Rodent, p. 747.) 



Hab. Ecuador ; Peru. 



Average length about 12*50 in., of tail-vertebrae 12-50. Upper 

 parts nearly uniform grizzled grey, rump and lower parts more or 



