CHAP, xi TEETH 509 



of Eustachian tube ; /. t. uterine tube ; g. b. pall-bladder ; h. p. hard palate ; 

 //. />*. bones of hard palate ; hy. hyoid ; t. incisors ; il. ileum ; t. n. passage of 

 internal nostrils ; _;'. Jacobson's organ ; k. left kidney ; I. au. left auricle ; Ing. 

 left lung, seen through pleura ; Ir. liver ; /. y 4 . fourth lumbar vertebra ; /. vn. 

 left ventricle ; m. tb. maxillary turbinal ; n. p. c. naso-palatine canal ; n. ph. 

 uaso-pharynx ; /. tb. naso-turbinal ; n. s. nasal septum (middle part cut away) ; 

 as. gullet ; ol. 1. olfactory lobe ; ov. left ovary ; p. a. pulmonary artery ; pc. 

 pericardium ; per. gl. perineal gland ; ph. pharynx ; phr. n. phrenic nerve ; 

 (origin not shown) ; p. m. a. posterior mesenteric artery ; p. mx. premaxilla ; 

 pn. pancreas ; pn. d. pancreatic duct ; pr. c. left precaval ; p. sy. pelvic sym- 

 physis ; pt. c. postcaval ; py. st. pyloric region of stomach; r. ribs ; ret. rectum ; 

 r. gl. rectal gland ; r. vn. right ventricle ; sk. f. floor, and sk. r. roof of skull ; 

 si. gl. sublingual gland ; s. mx. gl. submaxillary gland ; s. p. soft palate, ending 

 in the velum palati, on the lower side of which a tonsil is seen ; sp. c. spinal cord ; 

 sp. n. spinal (lumbar) nerves ; s. r. sacculus rotundus of ileum ; s. v. first sacral 

 vertebra ; sy. sympathetic (the anterior end shown on the right side, the rest on 

 the left) ; t. tongue ; thr. thyroid ; th v$. ninth thoracic vertebra ; thy. thymus ; 

 tr. trachea ; u. bl. urinary bladder ; ur. ureter ; ut. uterus ; vag. vagina ; vb. 

 vestibule ; vg. vagus (the anterior end shown on the right side, the rest on the 

 left) ; vul. vulva. 



papilla on its outer margin. The tongue (t) lies on the 

 floor of the rruouth to which it is attached below, its 

 anterior, rounded end being free : the surface of its 

 posterior part is elevated, and elsewhere but more 

 particularly on the tip its covering of mucous mem- 

 brane is produced into minute, finger-shaped papilla, 

 on which some of the microscopic organs of taste are 

 situated (compare p. 180). Taste-organs are also present 

 on a pair of circumvallate papilla on the dorsal side of 

 the tongue towards its posterior end, and on a pair of 

 transversely ridged areas the foliate papilla, situated 

 laterally, slightly anterior to the former. The main 

 substance of the tongue is composed of muscles, some 

 extrinsic, or arising from other parts, and others intrinsic, 

 or entirely confined to the organ in question. 



The teeth (Figs. 132 and 133), as we have seen, are 

 not all alike, as in the dogfish and frog ; there are 

 incisors and cheek-teeth or grinders, the latter being 

 divisible into two series the premolars and the molars. 

 In most Mammals there is also a pair of canine teeth 

 situated between the incisors and premolars, and these 

 are especially long and pointed in such carnivorous ani- 

 mals as the dog and cat. In the dogfish and frog, again, 



