494 DIGESTIVE SYSTEM OF THE DOG 
from the corner incisor by an interval into which the lower canine is received when 
the jaws are closed.!. The lower canine is close to the corner incisor. The root is 
about an inch (ca. 2 to 3 em.) long and is flattened laterally. 
The cheek teeth are typically &, but in brachycephalic breeds they are com- 
monly reduced to 2 and in extreme cases even to +. The reduction occurs at either 
end or at both ends of the series.2. The first tooth appears only once. The fourth 
tooth of the upper row and the fifth of the lower row are much larger than the rest, 
and are termed sectorial or carnassial teeth. From these the teeth diminish in size 
both forward and backward. The upper and lower teeth do not correspond, but 
rather dovetail. The teeth behind the sectorial ones are tuberculate, 7. e., have 
Fic. 435.—Sku.t or Aputt St. BERNARD Doc, Scutptvrep To SHow THE EMBEDDED PARTS OF THE TEETH. 
I1-8, Incisors; C, canines; P/-4, premolars; M1-—3, molars 
rounded eminences on the masticatory surface. The others are all sectorial in 
character, 7. e., have sharp-edged, pointed projections, the middle one being the 
most prominent. The premolars are laterally compressed, and are separated by 
intervals from the canines and from each other, except in the brachycephalic 
breeds. The upper molars have wide, somewhat quadrangular crowns, and three 
roots. The crown of the upper fourth premolar (Dens sectorius) is divided into 
two pointed lobes and has an antero-medial tubercle; it has three roots. The 
1In the bull-dog, which is very prognathic (‘‘undershot’’), the lower canines are opposit 
to or slightly in front of the plane of the upper incisors, and the upper canines are about opposite 
to the first lower cheek teeth. In the epignathic (‘‘overshot”’) dachshund the lower canines are 
under or slightly behind the upper ones. 
* Increase in number also occurs, the supernumerary teeth being at either end of the series. 
The occurrence of a third upper molar is not rare. 
