DISSECTION OF A TURTLE. 57 



the vessels. Trace them out, making out carotids, aortic 

 arches, and pulmonary arteries, comparing your work step 

 by step with the frog. (The third of the primary arches 

 has entirely disappeared.) What differences do you find 

 between right and left aortic arches ? 



In the body-cavity, behind, are the kidneys. Are they 

 smooth or lobed ? Where do their ducts empty ? Do you 

 find a urinary bladder arising from the intestine behind ? 

 The ovaries are a broad oval, and can usually be recognized 

 by the contained eggs. Where do the oviducts empty ? 

 The testes are smaller, long oval, and are outside and behind 

 the kidneys. 



In the skeleton * look for the vertebral column on the 

 inside of the carapace. Is it firmly united to it ? Can you 

 find any traces of ribs ? If so, in what respects are they 

 peculiar ? What parts can you recognize in the shoulder 

 and pelvic girdles ? In either limb, beyond the humerus 

 or femur, make out two bones (radius and ulna in the fore 

 limb, tibia and fibula in the hind limb), and beyond this 

 the (how many ?) carpal or tarsal bones. How does this 

 explain certain peculiarities in the frog? Draw either 

 limb, naming parts, remembering that the radius is on the 

 side of the thumb, the tibia on that of the big toe. 



In the skull is the socket (orbit) of the eye completely 

 enclosed in bone ? How does the lower jaw join the skull ? 

 What is the means for articulation of the skull with the 

 vertebrae of the neck ? Are the vertebrae of the neck hol- 

 low in front, behind, or on both surfaces ? What name is 

 to be given to the condition found (p. 52) ? 



* Skeletons sufficient for these purposes can readily be made by 

 boiling the specimens and washing away the flesh, with the aid of a 

 nail-brush. It is well to boil the head separately. 



