NO. 8 INTERRELATIONSHIPS OF THE CETACEA ^^'INGE 93 



Thalassocetus is based by Abel (Odontocetes du Bolderien, 1905. 

 pp. 70-74, with figures) on a few pieces of forehead of skulls from 

 the Tertiary deposits at Antwerp. Abel is no doubt right in consider- 

 ing it a near relative of Hoplocetus {" Scaldicefus ") ; but the genus 

 is too slightly known to be definitely placed. 



Prophyseter is based by Abel (Odontocetes du Bolderien, 1905, 

 pp. 82-85, with figures) on very imperfect remains from the Tertiary 

 deposits at Antwerp. If the interpretation of the bones is right 

 (whereof, according to the photographs, there seems to be some 

 reason for doubt) the remains represent two pieces (perhaps belong- 

 ing together) of the left side of a snout-tip, a piece of intermaxillary 

 and a piece of maxillary, both with alveoli but no teeth. Abel believes 

 that Prophyseter was a relative of Hoplocetus {'' Scaldicetiis"), but 

 that it had gone a step further in the direction of Physeter, since the 

 upper teeth had begun to degenerate. This refers to the fact that the 

 alveoli in the intermaxillary appear to be in course of obliteration 

 after the disappearance of the teeth. With regard to this there might 

 be other explanations also. The specimens are too doubtful for any- 

 thing final to be said about the animal's relationship. 



