900 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



base being posterior, the apex anterior, being joined to the pre- 

 maxillary. The superior surface is concave, the outer portion 

 bending upwards and inwards. It forms the floor of the nasal 

 cavity. The inferior surface is convex and forms a roof for the 

 nasal gland cavity of the vomer. The vertical portion is close to 

 the septum nasi, and rests on the vertical plate of one of the 

 vomers. 



Os Vomer. 

 Os Vomer, all authors. 



The vomers are constituted by two distinct bones, each of which 

 has a vertical and a horizontal plate. The vertical plate of each bone 

 approaches its fellow in the mid-line but is separated by a small 

 amount of tissue. Above the vertical plate is in contact with the 

 septo-maxilla and close to the nasal septum, while posteriorly the 

 parasphenoid articulates with it. 



The horizontal portion of the bone is triangular in outline, the 

 base being at the mid-line. The anterior extremity is sharp and 

 approaches close to the palatine process of the premaxilla. The 

 posterior extremity is rounded and fades into the vertical plate. 



The middle and external portion is convex below ; it runs out- 

 wards and curls upwards, its superior surface forming the floor of 

 the nasal gland, whose duct perforates the bone anteriorly. On 

 the inferior surface of the bone the spheno-vomerine muscle is 

 inserted. The nasal gland is contained in a box whose roof is 

 formed by the septo-maxilla, the inner and inferior sides by the 

 vomer, the external side being membranous. " Two small labial 

 cartilages are attached to the duct of each nasal gland " (Parker). 



Os Basisphenoideum. 



Corpus ossis sjyhenoidei, D' Alton; Sphenoideum hasilare, Hoff"- 

 niann, Hallmann, Harting, Stannius ; Spheyioideum, Cuvier, Joh. 

 IMiiller, Owen : Basisjyhenoid, Gegenbaur, Huxley, Parker, Parker 

 and Bettany, Wiedersheim ; Korper des KeVbeinstilckes, Meckel ; 

 KiJrper des vorderen, Korper des hinteren Keilheinsy Rathke. 



