RECORDS OF MEETINGS 249 



both sides. The ventral bar of the transverse process of the 7th cervical 

 vertebra was lacking, that of the sixth was retarded in development and 

 moveable upon the centrum. The pelvis showed no sign of an acetabu- 

 lum. There was no trace of a femur. 



The nasal fossa, larynx and ear were studied by Dr. John D. Kernan, 

 Jr., of Columbia University, whom I have asked to present his results as 

 a continuation of this communication. 



Dr. Kernan stated that the important thing to note in connection with 

 the ear of this animal is that it is of high mammalia type made over for 

 life in the water. The external ear has disappeared, and neither muscle 

 nor cartilages Avere observed in this foetus, although both have been re- 

 corded by other observers. The external auditory meatus is a very small, 

 tortuous passage capable of valve-like closure. In the foetus there is no 

 trace of the ceruminous mass found in the adult. The tympanic mem- 

 brane is of the ordinary mammalian type, attached by its margins to the 

 tympanic ring, concave externally, and attached to the manubrium 

 mallei by a triangular fold which appears to be a protrusion of the mem- 

 brane itself. The ossicles present no peculiarities. There is a well de- 

 veloped tensor tympani present, a fact which has not before been noted. 

 The cavum tympani is filled by a mass of cavernous tissue which is 

 thought to have the function of regulating pressure in the middle ear 

 during submersion of the animal. The internal ear shows a well de- 

 veloped semicircular canal system and a cochlea of nearly three turns. 



In considering these structures as an apparatus for hearing we see 

 at once that all possibility of hearing' by air conduction is shut off. It 

 seems as if rather elaborate precautions had been taken to prevent this. 

 In this connection it is interesting to recall that in diseased conditions 

 of the conducting apparatus in human beings the hearing by bone con- 

 duction is increased and prolonged. It may well be said that in whales 

 the closing off of the external auditory meatus increases the possibility 

 by bone conduction, on which they must depend for hearing water-borne 

 sounds. These are probably conveyed to the cochlea through the promi- 

 nent mastoid process which occupies a considerable extent of surface 

 between the squamosal and exoccipital bones. 



The Section then adjourned. 



William K. Gregoey^ 



Secretary. 



