416 AMERICAN TESTUDINATA. Part II. 



entirely inaccessible. I intended sinking a steel-trap, baited with beef, to secure 

 this sagacious old fellow, but my removal to the city side of the Colorado prob- 

 ably saved his life ; and I have but little doubt he yet lives and thrives upon 

 the numerous fishes I left with him. If these two turtles made a nest or 

 deposited their eggs while I had charge of them, I never discovered it. They 

 kept all their love for one another, and their domestic affairs, a profound secret 

 from their master. This species has a strong musky smell." 



A comparison of the young, (PI. 5, fig. 23-27,) and of the eggs, (PI. 7, fig. 

 27,) with those of Chelydra serpentina, (PI. 4, fig. 13-16; PI. 5, fig. 18, 19, and 

 PI. 7, fig. 24-26,) will suffice to show the difference between these two remark- 

 able Turtles. The color of Gypochelys lacertina varies from a light reddish or 

 yellowish brown to an almost black tint. 



II. Chelydra, Schw. 



The head is smaller in Chelydra than in Gypochelys, the difference lying 

 mostly in the relative size of the muscles which move the jaw, for the mouth 

 is much broader here than in Gypochelys. The upper surface does not, as in 

 Gypochelys, make an angle and lessen its descent in passing forward to the 

 region of the eyes, but continues with one slope from the hind to the front 

 end. The bony covering of the head, back of the eyes, is a low, flattened arch, 

 spread out widely below, the sides making a very slight angle with the upper sur- 

 face. The head widens downward also at the region of the eyes, and the orbits 

 are near together at their upper edges and wide apart below, so that the eyes 

 look upwai'd as well as forward and sidewise. The upper and hind edges of 

 the orbits project considerably beyond the skull, just between and behind them. 

 The spreading apart downward of the sides of the front part of the head 

 makes the mouth very broad. The nasal region is short, not high and flattened 

 sidewise, as in Gypochelys, but rounded and conical, with the front end trun- 

 cated. The outer surface of the jaw, at the front end, slants backward from the 

 nose to the alveolar edge. The alveolar edge is prolonged downward at the 

 symphysis to a small point ; and on each side of the point the curve of the sides 

 of the nasal region is continued down to the edge, and makes a short depres- 

 sion in it : the edge curves down only slightly under the eye. The pit, in the 

 alveolar surface at the front end, is very small. The pterygoids are broad 

 between the muscles of the jaw. The lower jaw, like the upper one, is spread 

 wider, and is lower and not so strong, as in Gypochelys. Its alveolar edge is 

 pointed at the symphj'sis ; but the point is very small, and reaches no higher 

 than the coronal angle. The ridges along the carapace are here less developed 



