MUSEUM OF COMPARATIVE ZOOLOGY. 235 



being a southern species, Massachusetts is probably its northern limit 

 Its occurrence here is comparatively rare. 



65. Fiber zibethicus Crv. Muskrat. Abundant. Individ 

 uals nearly black are taken occasionally. 



HYSTRICID-ffi. 



66. Erethizon dorsatus F. Cuv. (E. dorsatus and E. epixan- 

 thus Auct.) Porcupine. "Hedgehog." Occasional on the Hoosac 

 ranges. 



Professor Baird, in his description of this species,* thus observes : " Fur, 

 dark brown ; the long projecting bristly hairs dusky, with white tips ; spines 

 white, the points dusky. Xasal bones not more than one third the length 

 of the upper surface of the skull." He adds : " I regret not to have a suffi- 

 ciently perfect specimen of the common Eastern porcupine before me to 

 furnish a satisfactory description. The differences, however, from E. epi- 

 xanthus^ are not very great, consisting cltiejly in the color of the tips of the 

 long hairs, and one description will answer very well for both, except where 

 the peculiarities of each are specially indicated. The range of this spe- 

 cies is much more limited than previously supposed, as it is replaced west 

 of the Missouri by the E. epixanthus" 



He thus describes E. epixanthus, from several good specimens: "Gen- 

 eral color dark brown, nearly black; the long hairs of the body tipped with 

 greenish-yellow. Xasal bones nearly one half or two fifths the length of 

 the upper surface of the skull"; which he says are not more than one third 

 in E. dorsatus. Nine very fine specimens of E. dorsatus in the Museum 

 of Comparative Zoology, from Central Maine, show that the color of the 

 projecting bristly hairs is variable. In one they are enlirebj black, except 

 a very few about the head, which are tipped with lighter ; in another 

 those of the back are black, while on the head, sides of the shoulders, etc., 

 they are tipped with dull yellowish-white. Several have them of the 

 greenish-yellow supposed to characterize exclusively E. epixanthus; in 

 one or two only can they be called white, while in one these bristly hairs 

 are almost entirely absent, being quite so on the back. The quills usu- 

 ally project considerably beyond the fur, but are sometimes quite con- 

 cealed within it. Their color varies from white to dull yellow. Professor 



* Mam. X. Am., p. 569. 



t " E. epixanthus Brandt, M&n. Acad, de St. Petersbourg, 1835. 388, 416; Plate I 

 (animal) and Plate IX. Fig;. 1-4, skull." 



