160 BULLETIN OF THE 



lamina would appear to have the most strongly localized olfactory sig- 

 nifiance, and the projected parts or lobes to be in part pi'otectors of the 

 maxilloturbiuals, or highly specialized portions of the olfactory apparatus, 

 in animals remarkably endowed with the sense of smell.* 



Conclusions. 



From the foregoing statements it is evident that the ethmoid bone 

 varies greatly in its details in the Mammalia. While these variations 

 may not have yielded any clews to relationship of genera in addition to 

 those already entertained, they may nevertheless be said to present new 

 evidence by which old claims can be strengthened. It has been seen 

 that generalized forms, such as Sus, Equus, or Dicotyles, are related to 

 more specialized forms, such as Bos or Ovis, not only by the characters 

 yielded by the foot, the teeth, and the placenta, but by the ethmotur- 

 binal bones as well. In like manner, in a generalized genus of the Car- 

 nivora, as Ursus or Procyon, the ethmoturbinal bones possess a less degree 

 of specialization than in Felix in one direction, and in Phoca in another. 

 If the testimony in confirmation of such relations of these genera were 

 lost, it could be restated from the data obtainable from a study of the 

 ethmoidal plates. — In the hats a plan similar to the one existing in the 

 majority of the mammals is recognized in the Pteropidse and Phyllostomi- 

 didje (groups already known to be generalized), but which is strangely 

 departed from in highly specialized forms, as the Megadermatida? and 

 the Rhinolophidse, and in a widely different way in the Vespertilionidas, 

 — It has been found that in many of the Cheiroptera, generic and even 

 specific characters can be found in the ethmoid bone; and, on the whole, 

 it is temperate to affirm that a comprehensive account of any species of 

 bat would be imperfect which omitted an account of this bone. It is 

 probable that a similar statement might with propriety be made for all 

 mammals. Certainly it may be said that, in the study of those genera 



* The relation borne by the ectotnrbinals to the frontal sinus, by the sphenoturbi- 

 nals to the sphenoidal sinuses, and by the passages of access to the lateral part of the 

 ethmoturbinals to the maxillary sinuses, suggests the probability that the primary sig- 

 nification of these chambers is to accommodate the olfactory plates ; and that in the 

 human subject, where they are empty and not held subservient to the sense of smell- 

 ing, the original conception has been lost, owing to the stunted condition of the 

 olfactory apparatus. Until elaborate studies of the development of the mammalian 

 head are instituted with the object of confirming such a suggestion, but little can be 

 said about it in this connection. It must be remarked that the labors of Kitchen 

 Parker (loc. cit.) have not led to any affirmative answer to such a line of inquiry. 



