102 PROCEEDINGS OF tHE NATIONAL MUSEUM vol. i05 



Porpoises now allocated to th6 family Iniidae were well represented 

 and widely distributed during the Miocene and Pliocene. Neverthe- 

 less, the two known living forms are widely separated geographically, 

 the South American Inia geqffrensis being restricted to the Amazon 

 and the Orinoco Rivers and their larger tributaries, and the Chinese 

 Lipotes vexillifer being known only from Tung Ting Lake, Yangzte 

 River. Both of these Recent genera are confined to fresh water. 

 During the Miocene and Pliocene, some at least were inhabitants of 

 estuaries and others presumably were part of the pelagic fauna. 



Genus Lophocetus Cope 



Lophocetus Cope, Proc. Acad. Nat. Sci. Philadelphia, vol. 19, pp. 144, 146, 

 December 1867. 



Genotype: Delphinus calvertensis Harlan. 



Diagnosis: Skull strongly constructed, rostrum (389 mm.) equiva- 

 lent to not more than three-fifths of the length of the skull (es- 

 timated 630 mm.) ; vertex of skull elevated, elongated and comprised 

 by the large nasal bones, the exposed posterointernal angles of the 

 frontal bones and the apex of the supraoccipital; nasals large, elongated 

 anteroposteriorly and deeply depressed internally; no pronounced 

 thickening of supraorbital processes of frontals and overlying maxillary 

 plates; zygomatic processes elongated and relatively slender; rostrum 

 attenuated toward anterior extremity, with distal one-third slightly 

 bent upward; mesorostral gutter on anterior one-half of its length 

 roofed over by close approximation of premaxillaries ; posterior end 

 of each premaxillary upturned, forming an oblique crest, and is pinched- 

 in externally below crest; maximum transverse expansion of pre- 

 maxillaries immediately in front of nasal passages; 3 teeth located in 

 distal end of each premaxillary; 23 to 24 teeth located in each maxillary; 

 large lachrymal wedged in against preorbital portion of supraorbital 

 process and overlying ascending plate of maxillary, the antero- 

 posterior diameter apparently greater than transverse; jugal anky- 

 losed to lachrymal; palatines extending forward almost to level of 

 hindmost alveolae. 



Mandibles robust, with symphysis equivalent to one-third of the 

 length of each ramus; symphysis ankylosed, slightly narrowed at 

 anterior extremitj^, semicircular in cross section anteriorly, and with 

 anterior half of its length bent upward; lateral surfaces of symphysis 

 rugose; opposite free hinder portions of mandibles form an acute angle 

 at level where they ankylose as symphysis; 26 teeth in each mandible; 

 14 teeth located on each mandible posterior to hinder end of symphysis; 

 12 teeth located on each ramus anterior to hinder end of symphysis; 

 roots of teeth on symphysis implanted obliquely in alveolae, which 



