140 BULLETIN OF THE 



surface will be seen in the same specimen. Next, to make a trans- 

 verse (frontal) section of the opposite piece, in such a -manner as to 

 divide transversely all the parts of the ethmoid bone directly in advance 

 of the cribriform plate. The section must be made concentrically 

 to the plane of the cribriform plate, and of course to include the meso- 

 ethmoid. The proximal surface of such a preparation embraces a sec- 

 tion of the ethmoturbinals and of the septoturbinal space, and gives at 

 a glance the plan of the bone. The parts of both specimens can be han- 

 dled with freedom, as the botanist can press aside the several parts of a 

 flower, and afterward, without violence, return them to their natural 

 positions. 



If it be desired to retain the mucous membrane in connection with 

 the olfactory plates, the superficial parts, together with the temporal and 

 masseter muscles and the eyes, should be first removed to enable the 

 acidulated fluid to act directly upon the bony surfaces. After the bone- 

 salts have been dissolved, a saw may be employed to sever the denser 

 surrounding structures, such as the frontal bone, the zygomata, the hard 

 palate, etc., reserving the interior parts to be divided by the scissors or 

 the knife. By this means irregular laceration of the plates and mem- 

 branes is avoided, and the parts are kept free from bone-dust.* 



A General Account of the Ethmoid Bone. 



At the risk of repeating here and there a fact already incorporated in 

 the above list of terms, I will now give a succinct account of the eth- 

 moid bone, as studied in a number of well-known mammals other than 

 the bats. 



The Encranial Surface. — The cribriform plate is divided into two por- 

 tions, one lying over the septoturbinal space, and the other answering 

 to the ethmoturbinal spaces. The latter is again divided into two por- 

 tions, a superior and an inferior, which correspond to the ectoturbinal 

 and endoturbinal spaces respectively. In the Carnivora.f so far as exam- 

 ined, these divisions are abruptly angulated one to the other. The line 



* I desire to return my acknowledgments to the Academy of Natural Sciences 

 of Philadelphia for the use of crania from its collection. When it is seen that a 

 decalcified skull subsequently subjected to the making of sections of the etlimoidal 

 region is one practically expended in the cause of science, it will be conceded that no 

 inconsiderable privilege was accorded me. 



t For purposes of comparison, the ethmoid bone of the dog and otter are figured 

 side by side in Plate L But the bone of the otter is not separately described. 



