316 DISEASES OF DOMESTICATED BIRDS 
makes the corner of the mouth and limits the length of the beak ends 
is indicated in the anatomical drawing marked “ A.” The skin and 
lower jaw have been cut away in order that the position of the veins 
which lie far back on the roof of the mouth and just below its surface 
may be seen. The groove which occurs in the roof of the chicken’s 
mouth is a guide to the position of the blood vessel which it is desir- 
able to cut, this point being behind and to the left of the end of the 
groove when the chicken is held head down and with the lower side 
of the head uppermost. The direction and position of the cut which 
CORRECT CUT CORRECT CUT 
GROOVE “IN 
ROOF OF MOUTH 
EYE EYE 
ENO OF BEAK 
Fic. 66. Lower jaw removed, showing position of veins, anatomy of skull, and 
location of cut. (Pennington and Betts) 
is to sever the veins is shown in Fig. 66 to be on the left side of the 
chicken’s head when in the position just described. Because the 
short blood vessel connecting the two long veins, which we have 
termed the “ bridge,” does not run straight but at an angle, the point 
just indicated is farthest front and the most easily reached by the 
knife. As stated before, these veins lie just below the skin of the 
roof of the mouth, hence a deep cut is not needed, reither is any 
amount of strength required for the operation. 
It will be observed that just in front of the line which indicates the 
point at which these veins are to be cut they divide into two small 
branches, the course of which is not further shown. This is because 
they very soon pass through small holes in the bone and go into the 
