External Features. Ill 



(c) The nose (nasus), and its external apertures (nares an- 

 teriores) . 



(d) The eye (oculus), and its coverings, the eyelids, including 

 the upper eyelid (palpebra superior), the lower eyelid (palpebra 

 inferior), and the third eyelid (palpebra tertia). The third 

 eyelid occupies the anterior angle of the eye, and is compar- 

 able to the conjunctival fold of the human eye.' 



(e) The external ear (auricula), and its canal, the external 

 acoustic meatus (meatus acusticus externUs), leading to the 

 tympanic membrane. 



(f) Points on the head skeleton, to be identified by feeling 

 through the skin; zygomatic arch, supraorbital process, 

 external occipital protuberance, angle of the mandible, 

 symphysis of the mandible, and the hyoid bone. 



3. In the trunk: 



(a) The division into thorax, abdomen, and back, or dorsum. 



(b) The inclusion with the trunk of the proximal portions of the 

 limbs. The angle formed by the anterior limb with the trunk 

 represents the axillary fossa (fossa axillaris) . The depression 

 is much less evident than in man on account of the different 

 positions of its enclosing folds formed by the pectorales and 

 latissimus dorsi muscles. A corresponding inguinal furrow 

 separates the posterior limb from the abdomen and pelvis. 



(c) The anal aperture (anus), and on either side of it the inguinal 

 spaces, hairless depressions, on which the ducts of the inguinal 

 glands open. 



(d) In the male: the urinogenital aperture at the extremity of 

 the penis ; the latter enclosed by a fold of integument, the 

 prepuce (praeputium) ; the scrotal sacs (scrotum), lateral 

 sacs of the integument lodging the testes. 



(e) In the female: the urinogenital aperture, enclosed by folds 

 of the integument, forming the vulva. The clitoris, the 

 homologue of the penis, is contained in its ventral wall: The 

 mammary nipples (papillae mammarum), eight (to ten) in 

 number on the ventral surface of the breast and abdomen. 



(f) The following skeletal points: on the axial skeleton, the 

 manubrium sterni, xiphoid process, costal arch, spinous 

 processes of thoracic and lumbar vertebrae ; on the pectoral 

 girdle, the acromion, clavicle, and respective borders and 

 angles of the 'scapula; on the pelvic girdle, the iliac crest, 

 pubic symphysis, and ischial tuberosity. 



4. In the anterior limb : 



(a) The division of the free portion into three segments, the 

 arm (brachium), forearm (antibrachium), and hand (manus). 



(b) The position of the elbow (cubitus) in comparison with the 

 knee. 



