[390] 



THE 



NASAL KEGION IN EUTAENIA. 



— 



BY A. B. MACALLUM, B. A., High School, Cornwall, Ontario. 



The original object of the present paper was a description of the 

 Organ of Jacobson as it obtains in Entaenia. During the progress 

 of my studies in that direction, however, new features and modifica- 

 tions of previously described structures in the nasal cavity, lachry- 

 mal duct, and on the palatal surface, were observed, and I felt 

 compelled, in consequence, to abandon that limit, and to include 

 below a description of the whole Nasal Region. 



The material for study consisted of a series of sections from an 

 embryo-head, 6 mm. in length, of Eutaenia sirtalis, and several 

 series from the nasal region of adult forms of the same species. 



In addition to these, I have examined many of the parts in ques- 

 tion in fresh state in salt solution, and also when macerated. A 

 number of macerating reagents were employed, but treatment with 

 Midler's Fluid and subsequent staining with an alcoholic solution of 

 Eosin, gave the best results. 



I must here express my sincere thanks to Prof. Wright for the 

 kind advice and assistance received from him on points of this work, 

 and especially on the Organ of Jacobson, the structure of which I have 

 studied with him in his own laboratory. I am also indebted to him 

 for several of the drawings accompanying this paper. 



The roof of the mouth in the adult possesses several strongly 

 marked ridges and depressions. Of the former there are two on 

 each side of the middle line, that over which the maxilla lies being 

 the most prominent throughout. It runs parallel with the lip, and 

 does not unite with its fellow of the opposite side in front. The 

 palatine ridges commence some distance behind, are parallel to each 

 other, and bound a depressed palatal surface. Between the maxillary 

 and palatine ridges of each side lies another longitudinal depression 

 whose surface is striated, the course of the striation being obliquely 



