ON THE SINUS PARANASALES OF TWO EARLY 

 TERTIARY MAMMALS 



HOY L. MOODIE 



Department of Anatomy, University of Illinois, Chicago 



FIVE FIGURES 



It is generally supposed that the accessory nasal cavities of 

 mammals have had a long history, since they develop relatively 

 early in the embryo (Schaeffer, '10). It will be interesting to 

 note, in one of the two very early mammals described below, 

 the enormous development of these cavities. Fortunate casts 

 of the sinus paranasales of an oreodont (Merycochoerus) and 

 an early bear-dog (Daphaenus) came into my possession some 

 time since. In view of the active discussion in regard to the 

 morphology of these cavities in the vertebrate head, it is thought 

 that a discussion and illustration of these, the oldest known 

 paranasal sinuses, would be of interest. One of the casts is so 

 perfectly formed that the small bloodvessels (rami A. ethmoid- 

 alis anterior) of the mucous membrane (mucosa sinus paranasali) 

 lining the sinuses, are as sharp and distinct as if the sinuses were 

 of a recently dissected animal, in which the arteries had been 

 injected (fig. 1). 



A review of the literature of the sinus paranasales is not 

 necessary in this place, since this has been fully done by Kallius 

 ('05), who lists titles of four hundred and twenty-one studies 

 (1562-1905) dealing with this question. He has given further 

 the best pictures of the casts of these cavities, as they occur in 

 man, which have so far been published. The work of Schaeffer 

 ('10), Read ('08), Dieulafe ('06), Osborn ('12), and the writer 

 ('15), should be noted in this connection. So far as the writer 

 is aware, there has never been an attempt to study systemati- 

 cally the casts of the paranasal cavities of fossil mammals, mate- 

 rial for which is very abundant in the various paleontological 

 collections. It is a part of the purpose of this paper to call 



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