. Bulletin - United States National Museum. Science. 42 BULLETIN 171, UNITED STATES NATIONAL MUSEUM in several of those characters in which it differs from northern forms. Most noticeable among these are the size of the skull and canines, the development of the upper premolars, and the somewhat smaller relative size of the Figure 21.—Lutra parricu^pis Gidley and Gazln: Maxillary portion of skull with premolar and molar teeth, type specimen ( no. 8213), lateral and occlusal views. Natural size. Cumberland Cave Pleistocene, Maryland. A comparison of L. jparvicus'pis with L. rhoad
. Bulletin - United States National Museum. Science. 42 BULLETIN 171, UNITED STATES NATIONAL MUSEUM in several of those characters in which it differs from northern forms. Most noticeable among these are the size of the skull and canines, the development of the upper premolars, and the somewhat smaller relative size of the Figure 21.—Lutra parricu^pis Gidley and Gazln: Maxillary portion of skull with premolar and molar teeth, type specimen ( no. 8213), lateral and occlusal views. Natural size. Cumberland Cave Pleistocene, Maryland. A comparison of L. jparvicus'pis with L. rhoadsii Cope (1899, pp. 238-239) from Port Kennedy, Pa., is difficult on account of the different nature of the materials preserved. L. rhoadsii was based on lower jaws and a single upper molar. The dimensions given by Cope for the anteroposterior diameter of the lingual portion of M^ shows this tooth to be much smaller than in L. parvicuspis. Table 10.—Measurements (in millimeters) of superior dentition of three species of Lutra Measurement Length of cheek-tooth series, P' to M', inclusive C, anteroposterior diameter of alveolus P», anteroposterior diameter. P', greatest transverse diameter .- P', anteroposterior diameter P3, greatest transverse F*, anteroposterior diameter P«, greatest transverse diameter perpendicular to outer wall Ml, anteroposterior diameter across outer cusps M', anteroposterior diameter across inner portion Ml, transverse diameter across paracone and Lutra parrkuspis no. 821-3 (type) ' • 5 4 8 Lutra canadensis no 197943 () 30 5 5 Lutra friina no. 35377 () 33. G 5 6 > Approximate. Satherium piscinaria (Leidy, 1873, pp. 230-231) from the late Pliocene or early Pleistocene of Idaho is a considerably larger form as indicated by the size of the tibia. (See also Gazin, 1934, pp. 143-149).
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