EMYSTROOSTII. 57 



is lengthened out into a narrow line along the lateral and superior part of the 

 neck; another and more distinct greenish-yellow line is observed along the lateral 

 and inferior part of the throat, increasing in size to the junction of the jaws, where 

 it subdivides into two branches; the one going to the upper jaw, terminates at its 

 posterior part, that running to the lower jaw, ends midway between the condyle 

 and symphysis. Beginning at the chin is another broad pale straw-coloured hne, 

 which subdivides after a short distance, the branches continuing along the inferior 

 surface of the neck; a third line begins near the point of subdivision of the last, 

 small, but increasing in breadth, and running nearly in the middle of the inferior 

 surface of the neck; between these lines are many intermediate ones, smaller and 

 less distinct. 



The anterior extremities are black in front, with a broad palish straw-coloured 

 band near the lower part; the inferior border is yellow; the posterior surface 

 blackish-brown. The posterior extremities are black above, with a yellowish line 

 along the posterior margin of the thigh, and blackish below with two or three 

 interrupted yellow lines. On the lower extremity of the thigh is a large triangular 

 spot; the apex of which triangle is continued into a line along the anterior and 

 inferior border of the leg to the root of the first toe. The tail is black above, and 

 blackish-brown beneath with blotches of greenish-white; towards the extremity 

 on each side is a lateral yellowish-green line. 



Dimensions. Length of shell, 8 inches; greatest breadth, 7i inches; length of 

 sternum, 6^ inches; length of tail, 2| inches; length beyond the vent, 1^ inch; 

 height of the animal, 2| inches. 



Geographical Distribution. These animals abound in our western rivers. 

 The accompanying plate was taken from a fine specimen sent me from the 

 Cumberland river by Professor Troost, who has done so much to elucidate the 

 natural history of that part of the United States, and to whom I have dedicated 

 the species. 



Vol. I.— 8 



