THE HISTORY OF WHALES— THEIR ADAPTATION TO 

 LIFE IN THE WATER (Concluded) 



By REMINGTON KELLOGG 



Bureau of Biological Survey, United States Department of Agriculture 



PLATANISTIDAE 



THERE does not appear to be 

 any single directive trend in 

 the line of development that 

 regulated the overlapping or 

 telescoping of the major bones in the 

 odontocete skull, but on the contrary 

 telescoping has given rise to many different 

 types of skulls, and of these none are more 

 unusual than that of the Maryland 

 Miocene porpoise, Zarhachis flagellator 

 (Kellogg, 192.4; 19x6). An extreme 

 stage in the lengthening of the rostrum 

 is represented by this skull, and appears 

 to mark the culmination of the long- 

 snouted type of porpoise. The skull is 

 nearly four feet long with the rostrum 

 fully five times as long as the braincase. 

 Mechanical difficulties would interfere 

 with a further lengthening of this type of 

 rostrum. While the family position of 

 this porpoise may be a matter of personal 

 opinion, the periotic bone is similar to 

 that of Platanista, and cranial peculiarities 

 also indicate that it should be referred to 

 the family Platanistidae. 



According to our present knowledge, 

 Zarhachis flagellator represents a highly 

 specialized aberrant type that possesses 

 certain fundamental characters in common 

 with the living Ganges porpoise Platan- 

 ista gangetica. No fossil porpoises of this 

 type have been described from Miocene 

 formations of Europe and it may have 



been a migrant from some other region, 

 possibly the South Atlantic, which came 

 into association with the more widely 

 distributed types during the latter part 

 of the Miocene period. In its general 

 features the skull of Zarhachis is character- 

 ized by the presence of a pair of crescentic 

 orifices inclosed by ectethmoids on the 

 anterior wall of the braincase; maxillaries 

 expanded laterally behind the antorbital 

 notches with their lateral borders turned 

 upward to sheath the internal surfaces of 

 the up-built supraorbital processes of the 

 frontals, and in contact posteriorly with 

 the supraoccipital; small elevated vertex; 

 pterygoid with well developed external 

 reduplication, which extends from the 

 squamosal to the median line of palate at 

 a level considerably in advance of antor- 

 bital notch, concealing the alisphenoid 

 and palatine bones; palatine bone forming 

 part of the anterior wall of narial passage; 

 total number of teeth in excess of 300; the 

 enamel crowns of teeth ornamented with 

 longitudinal striae and the roots slightly 

 thickened. The symphysis is equivalent 

 to more than two-thirds of the total 

 length of either mandibular ramus. The 

 cervical vertebrae are free, and the dorsal 

 and lumbar vertebrae have broad flattened 

 neural spines. The path or paths of de- 

 velopment followed by the descendants 

 of this extinct porpoise are unknown at the 

 present writing. 



The existing Platanista gangetica 



*74 



