EXTERNAL ANATOMY OF THE VERTEBRATES l (2) 



A. Reptilia 



1. Examine a small Turtle and note: (a) the general form of this 

 animal encased in (6) the heavy box-like shell composed of (c) a dorsal 

 portion (carapace) and (d) a ventral portion (plastron) ; (e) the highly 

 developed head with (/) a long flexible neck ; (g) the clawed penta- 

 dactyl limbs; and (h) the short tail. Note (£) the scaly character of 

 the skin on the uncovered parts of the body. 



2. Examine the flattened, triangular-shaped head and note the follow- 

 ing structures: (a) the large mouth with heavy jaws, but no teeth; 

 (6) the pair of dorsal olfactory openings (external nares) ; (c) the 

 tympanic membrane on either side of the head, posterior to the attach- 

 ment of the lower jaw ; (d) the eyes protected by (e) upper and lower 

 eyelids and (/) a nictitating membrane which moves laterally to 

 cover the eye. Draw in outline to show general structure. 



B. Aves, or Birds 



3. Examine a Pigeon and note the general form of this animal and 

 the external covering composed of the unique exoskeletal structures, 

 feathers, which are found only on Birds. Note the division of the body 

 into head, neck, trunk, and short tail. Examine the clawed, four- 

 digited hind limbs which are adapted for bipedal locomotion, and the 

 greatly modified fore limbs, or wings, which are adapted for flying. 

 Examine the different types of feathers on various regions of the body. 



4. Examine the small head, and note the mouth with a projecting horny 

 structure (beak) which is an anterior continuation of the bony toothless 

 jaws. Identify the olfactory openings, the auditory openings, and 

 the eyes with upper and lower eyelids and nictitating membrane. 

 Draw in outline to show general structure. 



C. Mammalia 



5. Examine a small Mammal, such as a Rat or a well-developed fetal 

 Pig, and note the general form of this animal covered with the unique 

 exoskeletal material (hair) which is found only on Mammals. Note the 

 divisions of the body into head, neck, trunk, and flexible tail. Ex- 

 amine the fore and hind limbs, all of which are adapted for quadrupedal 

 locomotion. Examine the head. Note the mouth with well-developed 

 jaws and teeth, the olfactory openings, the auditory openings with 

 external ears, the eyes, with upper and lower eyelids. Draw in outline 

 to show general structure. 



6. Construct a table which will show in a comparative way the chief 

 external structural features of the six Vertebrate types studied in this 



and the previous exercise. 



1 B. pp. 157-164. 

 313 



