NO. 8 INTERRELATIONSHIPS OF THE CETACEA WINGE 79 



Pontoplanodes. At present the problem cannot be said to be 

 solved; but there appears to be no good reason to doubt the 

 correctness of Burmeister's determination. In the present paper 

 his presentation of the subject is followed. A piece of the beak 

 of Saurodelphis with the 8-shaped alveoli is in the Copenhagen 

 museum. 

 Gerrit S. Miller: A new River-Dolphin from China; Smithsonian 

 Misc. Coll., vol. 68, No. 9, 1918, pp. 1-12, pis. 1-13. Lipotes. 

 Ischyrorhynchus was based by Ameghino (Caracteres diagnosticos 

 de cincuenta especies nuevas de Mamiferos fosiles argentinos ; Revista 

 Argentina de Historia Natural, vol. i, 1891, pp. 163-165, with illus- 

 trations) on the anterior part of a lower jaw from the " oligoceno 

 inferior del Parana." The branches of the jaw, which are rather 

 heavy, are grown together in a long symphysis menti ; the rows of 

 teeth are further apart than in Saurodcphis (Saurocetes), with which 

 Ameghino associates the genus, and the roots in cross-section are 

 almost what might be called ovate, not 8-shaped ; the crowns are 

 known only imperfectly. It is not possible to decide where the genus 

 belongs. 



Pontivaga was also based by Ameghino (/. c, pp. 165-166, with 

 illustration) on the anterior part of a lower jaw, from the " oligoceno 

 superior " at Parana. The branches of the jaw are slender and are 

 grown together in a long symphysis. Each of them contains a long 

 row of small teeth, to judge by the alveoli. Ameghino places the 

 genus in the Platanistidcc, in contrast with the SaurocetidcE, whether 

 rightly or not cannot be said. 



A genus Proinia is established by True (A new genus of fossil 

 Cetaceans from Santa Cruz Tetritory, Patagonia, etc. ; Smithsonian 

 Misc. Coll., vol. 52, pp. 441-447, pi. 43, 1910) , y^ho regards it as a near 

 relative of Inia. Perhaps True is right ; but the material on which 

 the genus is based, a few fragments of a braincase and a cervical 

 vertebra all distorted by pressure, is so scanty that an error is very 

 possible. 



Hesperocetus is established by True (A fossil toothed Cetacean 

 from California, etc.; Smithsonian Misc. Coll., vol. 60, No. ii, 1912, 

 pp. 1-7, pis. 1-2) on the strength of the anterior part of a long, nar- 

 row, lower jaw with long symphysis, with rows of rather strong, 

 conical, slightly hooked teeth with wrinkled enamel. The teeth are 

 placed rather wide a,part and are separated by shallow depressions in 

 the margin of the jaw into which the tips of the upper teeth pre- 



