98 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Reports do not undertake to account for the incised condition of the 

 pair of ear-bones from Station 286, and show the grooved aspect of only 

 one of them in Plate 7, Fig. 5, of their Report. In the explanatory 

 legends, however, it is stated that " the markings shown in Fig. 5 were 

 found on both of the bones, and are of the same character ; these are 

 the only bones taken during the cruise with such marks, and they differ 

 from all the other ear-bones in other respects as well as in the markings." 

 Professor Thoulet's interpretation is expressed in such positive terms, 

 and is accepted with such readiness by Dr. Portis, that his views may 

 best be set forth in his own words, as follows : 



Une figure de MM Murray et Renard represente un os de baleine sur lequel sont 

 indiquees des marques arrondies, se coupant mutuellement et ressemblant a s'y 

 meprendre aux incisions couvrant une onioplate de Balaenotus tertiare trouvee a 

 Monte-Aperto, en Italia, par M. Capellini. M de Quatrefages s'etait justement 

 base' sur ces dernieres pour admettre I'existence de I'lionime tertiare, car il se 

 de'c'Iarait dans I'impossibilite de les attribuer a une autre cause qu' a Taction d'un 

 instrument tranchant. L' eohantillon du Challenger, autant qu 'il est perniis d'en 

 juger sur des dessins, parait resoudre la question de la maniore la plus nette et 

 contrairement aux conclusions de M. de Quatrefages; les incisions ne peuvent etre 

 que la trace des dents de Squales. 



The abo\e explanation would undoubtedly answer for any other por- 

 tion of the skeleton except dental tissue and bones of the auditory 

 region. Its inapplicability to the latter may be demonstrated by a 

 simple experiment. One may take any kind of shark's tooth whatso- 

 ever, recent or fossil, and try to obtain similar channelings and indenta- 

 tions on Cetacean ear-bones by forcible rubbing of the parts together. 

 It will be fomid that the surface of the ear-bone is barely scratched by 

 the apex of the enameled crown ; and that, as between the two bodies, 

 the shark's tooth is the more easily worn away. 



tlius confirming a conjecture made fifteen yearsearlier by Delfortrie. The latter's 

 publications are to be found in the Actes de la Societe Linneenne de Bordeaux, 

 (1869-72), 27, 28. 



