1-44 BULLETIN OF THE 



appear to be absent in the ape, at least in the adult. In man they 

 are also absent. The opossum has two ectoturbinals ; the cat, two to 

 three ; the hog, five ; the ox, eight. In the seal the ectoturbinals are 

 developed to a greater degree than the endoturbiuals. 



The olfactory plates are either simple at their ends or convolute. 

 Their anterior ends are often produced forwards in a series of tongue- 

 like projections, which have received the name of the olfactory lobes. 

 The projection known as the nasoturbinal is the most conspicuous of 

 these. The lobe on the first endoturbinal is always well developed. 

 The endoturbiuals of the hog are without marked lobulations. The 

 Carnivora and the Rodentia, as far as examined, possess lobes on all 

 the folds. In the opossum two of the plates are simple, the remainder 

 are convolute. Occasionally a convolute fold arises from the side of a 

 plate instead of from the end, as in the larger plates of the Carnivora 

 and the Ruminantia. The arrangement of the endoturbinals, as seen in 

 the median surface of the ethmoturbinals, is much the same as in other 

 Carnivora. 



The septoturbinal space is in all mammals narrow, and indeed may be 

 obliterated here and there where the endoturbinal plates lie in contact 

 with the septum. Such a point of contact is evident in the macaque, 

 M. nemestrinus, where a depression is seen on the septum answering in" 

 position to the first endoturbinal plate. Similar depressions are seen in 

 the bats, as in Antrozous and Corynorhinus. 



In Cebus (Plate II. figs. 1, 2) the absence of an ectoturbinal series, and 

 the endoturbinal series being restricted to a single plate bearing incisures 

 upon its posterior border, and retaining upon its anterior surface a de- 

 flected and abortive nasoturbinal (uncinate process), an example is afforded 

 of the manner after which the ethmoid bone is modified in passing from 

 the quadrupedal form to the primate. In man the interval between the 

 endoturbinal series and the lateral aspect of the bone is occupied by a 

 number of cellules. These being absent in Cebus and Macacus (the only 

 genera examined), it would appear as though the chief difference be- 

 tween these forms and the human ethmoid lay in the development of 

 the ethmoid cells. 



The human ethmoid bone (Plate II. fig. 3), viewed from beneath, fur- 

 nishes, as in Cebus, an aborted nasoturbinal in the " uncinate pr<> 

 and the rug086 under surface of the single endoturbinal plate in the 

 " middle turbinated bone." 



A Special Account of (he Ethmoid Bone ?'// the Horse, tht Peccary, the 

 Sloth, the Cat, the Seal, '""' the -!/"/<'. — I have thus endeavored to 



