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JOURNAL OF MAMMALOGY 
crowded, instead of small and well spaced. The intermaxillaries in 
profile do not curve upward so abruptly, their outline as seen from 
above is different, and there is no such marked asymmetry as shown 
in P. inaequalis. The latter in its greater specialization seems to be 
a more progressive species, as might perhaps be anticipated from 
its supposedly later geologic appearance (upper Miocene or lower 
Pliocene). 
The peculiar vertical implantation of the mandibular teeth, and the 
fact that at least the more proximal close within the maxillary rows, 
suggest a possible relationship to Platanista, in which exactly these 
conditions occur at the base of the beak, although in other respects 
the latter genus shows far greater specialization, as in the greater 
compression from side to side, of the entire rostrum. The« develop- 
ment of its characteristic maxillary crests seems of less systematic 
importance, for incipient crests are found in Phoccena on the intermaxil- 
laries, and very large ones in Hyperoodon on the maxillary bones. 
PHYSETERID^ — Sperm whales 
Diaphorocetus mediatlanticus (Cope) 
Plate 9, fig. 6; Plate 12 
1895. Paracetus mediatlanticus Cope, Proc. Amer. Phil. Soc., vol. 34, p. 135. 
1902. Hypocetus mediatlanticus Hay, Bull. U. S. Geol. Surv.,'no 179, p. 596; 
Case, Md. Geol. Surv., Miocene, 1904, p. 30, pi. 17, figs. 6a, 6b. 
1904. Hypocetus atlanticus Case, Md. Geol. Surv., Miocene, expl. of plates, p. 9 
(errorim). 
1898. Diaphorocetus mediatlanticus Trouessart, Cat. Mamm., new. ed., p. 1053; 
3d ed., 1905, p. 772. 
To this genus and species are referred a fragment of the lower jaw, 
including both rami, from the phosphate beds at Brewster, Polk County, 
and a second fragment comprising the occipital condyles, from Mul- 
berry. Apparently pertaining to the same species is the beautiful 
specimen figured by Sellards (1915, p. 103, fig. 32), also found at Mul- 
berry, consisting of the basal portion of the rostrum including both 
upper and lower jaws. Most unfortunately, this piece, which was 
for a time in the possession of the International Agricultural Corpora- 
tion, has been disposed of and cannot be traced. 
The genus Hypocetus was established by Lydekker in 1893, as a 
substitute for Mesocetus (preoccupied) of Moreno (1892), type Meso~ 
cetus poucheti, a medium-sized cetacean of the sperm-whale family, 
