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Show 332 Measurements of eighteen skulls of LUTRA CANADENSIS. II Locality. 2 He marks. 501 498 500 490 555 556 557 559 558 489 4446 11839 3247 13671 8097 433 3142 Newfoundland do do do Umbagog Lake, Maine do do do do do Lake Superior Fort Berthold, Dak Saranac Lake, New York Bayfield, Wia Fort Cobb, Indian Ter Washington, D. C do Saint Simon's Island, Georgia . 4.90 4.03 4.15 4.35 4.40 4.27 4.50 3.97 3.96 4.50 4.15 4.25 4.05 4.06 4.22 4.50 4.45 4.32 2.75 8.53 2.57 2.90 a oo 2.85 2.90 2.70 2.70 3.00 2.85 2.82 2.57 2.82 2.87 2.95 2.75 Imperfect. MEPHITIS MEPHITICA. The twenty- nine skulls of this species of which measurements are given below show a wide range of variation in size, and a decided decrease southward. The localities embrace such distant points as California and the Atlantic seaboard on the one hand, and Maine and Texas on the other; bat, with one or two exceptions, the specimens from any single locality are unsatisfactorily few. The specimens range in length from 2.60 to 3.50, and in width from 1.60 to 2.25! Yet there is not a specimen included in the series that is not so old as to have all the cranial sutures obliterated. A portion of the difference is doubtless sexual, but the specimens, unfortunately, have not the sex indicated. Ten of the specimens may be considered as western, coming mainly from Utah and California; ten others are from Maine and Massachusetts, and one from Northeastern New York; three are from Pennsylvania; and of the remaining five, four are from Texas, and one from Louisiana. The western series of ten average 3.10 in length and 1.95 in width, ranging in length from 2.85 to 3.50 and in width from 1.70 to 2.25. The New England series of ten average 2.88 in length and 1.72 in width, ranging in length from 2.70 to 3.25 and in width from 1.53 to 1.85. The single New York specimen scarcely varies from the average of the Uew England series, while the Pennsylvania specimens fall a little below. The five southern specimens average 2.73 in length, or a little below the New England series, ranging in length from 2.60 to 290.* It thus appears that the western specimens are decidedly the largest of all, and that the northern are somewhat larger than the southern, the specimens compared being of corresponding ages, though of unknown sex, but doubtless comparable in this respect also. The difference in size amounts to above one- fourth the size of the largest specimen and above one- third the size of the smallest Between the western and southern series, the average difference amounts to one-third of the average size of the larger series! The western series includes the so- called Mephitis occidentals of Baird, based on California specimens, and whose chief difference is merely that of larger size; yet the four specimens from Ogden, Utah ( Coll. Mus. Gomp. Zoo!.), considerably * The range in width is not fairly indicated, owing to two of the smaller specimens ^ eing imperfect. |