THE SKELETON OF THE DOG. THE SKULL. 395 



turbinal bones, which have a curious character, being formed 

 of a number of delicate plates intimately folded on one 

 another. The posterior pair of these bones, the ethmo- 

 turbinals (fig. 72, 10), are the larger, and form a mass of 

 intricately folded lamellae attached behind to the cribriform 

 plate, and passing laterally into two thin plates of bone, 

 which abut on the maxillae. The uppermost lamella of each 

 ethmo-turbinal is larger than the others and more distinct. 

 It is sometimes distinguished as the naso -turbinal, and forms 

 an imperfect lower boundary to a canal, which is bounded 

 above by the nasals. In front of and somewhat below the 

 ethmo-turbinals, lie another pair of bones of similar character, 

 the maxillo-turbinals (fig. 72, 11). 



The last bone to be mentioned in connection with the 

 olfactory capsules is a membrane bone, the vomer (fig. 72, 9). 

 This is a slender vertically-placed bone, whose anterior part lies 

 between the maxillo-turbinals, while behind it extends beyond 

 the mesethmoid, so as to underlie the anterior part of the pre- 

 sphenoid. The anterior part of the vomer forms a kind of 

 trough, while further back in the region of the ethmo-turbinals 

 it sends out a pair of strong lateral plates, each of which, 

 passing below the ethmo-turbinal, joins the side wall of the 

 nasal cavity, and forms a partition dividing the nasal 

 cavity into a lower narial passage and an upper olfactory 

 chamber. 



THE JAWS. 



In the embryo both upper and lower jaws are formed of 

 cartilaginous bars, but in the adult not only has the cartilage 

 entirely disappeared, but even cartilage bone is absent, the 

 jaws being formed of membrane bone. 



3. THE UPPER JAW. 



The bones of the upper jaw are closely connected with 

 those of the cranium proper and olfactory capsules. The most 



