a. Upper mandible. 
b. Lower mandible. 
c. Culmen. 
d. Gonys. 
e. Nostril. 
f. Nasal fossa. 
g. Commissural point. 
h.  Rictus. 
j. Upper tomium.—pl. tomia=sharp cutting edge. 
k. Lower tomium. 
Kinds of bills of birds— 
1, Fissirostral. 2, tenuirostral. 3, Dentirostral. 4, Conirostral. 
5, Pressirostral. 6, Longirostral. 7, Cultrirostral. 8, Lamellirostral. 
