REPTILIA 



307 



The soft-shelled turtles {Aspidonectes feros) are edible forms 

 found from South Carolina to Texas and up the Mississippi to the 

 Great Lakes. They weigh as much as 30 pounds. They are omniv- 

 orous, feeding on Crustacea and insects, but also destroying fish 

 and waterfowl, since they are extremely fast swimmers. 



Type— The " Slider" Terrapin {Pseudemys rubriventris) .—The 

 turtle has no teeth, but horny jaws. Its tongue is broad and soft, 

 and the pharynx is thin walled and distensible. The thick-walled 

 esophagus bears papillae. The stomach has a pyloric valve. The 

 small intestine consists of the duodenu7n, ileum, with an ileocecal 

 valve, large intestine and rectum. There are paired cloacal sacs and 

 the respiratory system consists of the glottis, larynx, trachea and two 

 bronchi. The lungs are large and many branched. The hyoid 

 apparatus supports the larynx. Movements of the hyoid, neck 

 and anterior limbs aid in respiration. 



Aquatic tortoises and marine turtles have two large sacs at- 

 tached to the cloaca. These are filled with water and richly vascular. 

 At times, when water is replaced by CO2, they may buoy up the shell 

 and supplement the lungs. Females are said to utilize the liquid in 

 these sacs in wetting down the eggs deposited in sand on the shore. 



The heart has two auricles and incompletely divided ventricles, 

 the septum being perforated. The venous blood passes from the 

 postcaval and two precaval veins into the sinus venosus and thence 

 to the right auricle. From the right auricle it flows to the right side 

 of the ventricle. 



From the right ventricle it goes to the puhnonary artery which 

 divides on the right and left; and also through the left aorta which 

 sends blood to the viscera and into the dorsal aorta. The left arch 

 is therefore venous to the alimentary canal by way of the coeliac. 

 Purified blood from the lungs passes to the auricle and left side of 

 the left ventricle. The blood then goes through the right aortic arch 

 to the dorsal aorta. It is impure, because mixed in the ventricle. 

 The turtle has no renal portal, but the usual hepatic portal system. 



Urinogenital Organs. — The urinary system consists of paired, 

 reddish, oval kidneys, paired ureters, a urinary bladder shaped like a 

 dirigible balloon, the cloaca, oval in shape, and the anus. 



The testes are oval, yellow bodies with vasa deferentia leading 

 to the grooved penis which is attached to the anterior wall of the 

 cloaca. The paired ovaries are rather diffuse, somewhat resembling 

 the single left ovary of the bird. The oviducts open into the cloaca. 



