ALLEN : MAMMALIA : OCTODONTID^. 37 



new species. His most important character is the presence of a deep, 

 longitudinal sulcus on the upper side of the jugal. It is true that this is 

 not shown in Bennett's figure, which is only slightly shaded, being mainly 

 in outline ; but I find this same sulcus is present, in a more or less marked 

 manner, according to the age and sex of the animal, in all of my large 

 series of the genus Ctenoniys from Patagonia, which includes over fifty 

 skulls, representing several more or less closely related forms. I have, 

 therefore, no hesitation in regarding Nehring's C. 7icglectus as based on 

 an adult female skull of one of the larger Patagonian species, in all 

 probability C. niagelhmicus, although no definite locality is given for the 

 specimen. 



Ctenomys fueginus Philippi. 



Ctenomys fucgimis Philippi, Arch. f. Naturg., 1880, i, 276, pi. xiii, skull. 

 Tierra del Fuego. — Lahille, Congr. Cien. Lat. Amen, III, 1899, 190. 



Above mixed yellow and gray varied with black, the basal two thirds of 

 the pelage blackish, with a subterminal band of white or light yellow, 

 and the tips black ; ventral surface white, the basal half of the pelage black 

 and the apical half white ; tail well clothed with soft hairs, above blackish, 

 especially towards the tip, below clear yellowish white. 



Measurements. — Head and body, 227 mm. ; tail, 46 (= total length, 

 273) ; fore foot to end of claws, 26; longest fore claw, 10 ; hind foot, 35 ; 

 longest hind claw, 6. Skull : total length, 49 ; zygomatic breadth, 28.5 ; 

 mastoid breadth, 26. (Based on Philippi, /. c.) 



This species was founded on specimens collected by Lieutenant Serrano 

 of the Chilian Navy in the summer of 1878-79, on " der ostlichen Insel 

 des Feuerlandes," and was described and the skull figured by Professor 

 Philippi in 1880 (/. c). 



In general appearance he found it not very different from the other 

 species of the genus ; his comparison of it, however, with C. niageUanicus 

 was made, in the absence of specimens, with Waterhouse's description and 

 figure. He found the dimensions of the skull somewhat larger in C. fue- 

 ginus than in C. niagellanicus, and the zygoma outwardly more convex, as 

 shown by his comparative figures of the skulls of the two species (/. c, pi. 

 xiii). But these differences are not necessarily important, since they are 

 found in allied species to characterize the two sexes of the same species. 

 Other coordinated differences are noted, so that he felt fully warranted in 

 treating the Tierra del Fuego animal as distinct. 



