NO. 1875 



NEW FOSSIL CETACEAN — TRUE 



447 



in outline anteriorly and posteriorly, but the upper margin is more 

 or less rounded. The two sides of the centra below the transverse 

 processes are quite concave, but without distinct channels. 



The foregoing combination of characters appears to me to indicate 

 a relation to some of the North American forms which have been 

 assigned to the nominal genus Priscodelphimis, such as P. hawkinsi, 

 harlani, etc. 



The dimensions of the vertebras are as follows : 



Dimensions of five thoracic vertebrcs, iVo. iS439 



Length of centrum 



Height of anterior face of centrum 



Breadth of anterior face of centrum 



Height of posterior face of centrum 



Breadth of posterior face of centrum 



Height to anterior extremity of metapoph- 

 ysis 



Projection of metapophyses anteriorly be- 

 yond margin of neural arch 



Breadth of neural arch at base, antero-pos- 

 teriorly , 



Breadth of neural canal anteriorly 



Breadth of neural canal posteriorly 



Antero- posterior breadth of neural spine 

 in a horizontal line immediately above 

 zygapophyses 



Breadth of transverse process at base 



Breadth of transverse process at extremity.. 



39 



45 



52 



42.5 



50.5 



71 



13+ 



29 



26.5 



26 



48 

 34 



28(?) 



40 



45 

 52 

 46 

 52 



74 



23 



29 

 22 



24 



47 

 33 

 26 



mm. 

 40 

 47 

 54 



54 



30 

 20 

 20 



35 



turn. 

 40 



54 

 45 

 54 



73 

 21 



31 



235 



32 



45 

 49 

 55 



47 

 57 



74{?) 



27 

 16 



34 

 35 



PROSQUALODON AUSTRALIS Lydekker 



Prosqualodon australis Lydekker, Anal. Mus. de la Plata, Pal. Argentina, 

 vol. 2, art. 2, p. 8, pi. 4, Apr., 1894; Proc. Zool. Sec. London, 1899, p. 919, 

 figs. I, 2. 



The material turned over to me for study by Professor Scott in- 

 cludes portions of the skeleton of this species, comprising (i) a por- 

 tion of the right half of a mandible with two teeth in position; (2) 

 a portion of a left ramus 1(3) eight separate teeth ; (4) a nearly per- 

 fect atlas and two thoracic vertebrae; (5) two pieces of ribs; (6) a 

 tympanic bone; (7) a periotic bone. These were collected from the 

 Patagonian beds at San Julian, April 22, 1899, by J. B. Hatcher. 



A detailed comparison of these remains with Doctor Lydekker's 

 figures and description leaves no doubt in my mind that they repre- 

 sent Prosqualodon australis. The right ramus of the mandible is 

 nearly complete posteriorly, the coronoid process being perfect and 



