TURTLES AND TORTOISES 15 



ranges from southern New York to the Gulf of Mexico 

 and westward to the Mississippi Valley. The upper 

 shell is broader and more flattened than that of the musk 

 turtles; with the latter this species might be confused, 

 but the wide plastron forms an unfailing mark for dis- 

 tinction. On the carapace of the young are three faint 

 keels ; adults show no traces of any but an obscure cen- 

 tral keel. Above, the color is dull olive or brown, the 

 shields narrowly margined with black. Most specimens 

 have the head speckled. 



The Louisiana Mud Turtle, C. louisiance, appears 

 to be closely allied to the preceding. Distinguishing 

 marks are the more elongated shell and the arrangement 

 of the colors on the head in broad, orange bands. In 

 the lower Mississippi Valley it is a common turtle. 

 Baur's Mud Turtle, C. hauri, inhabits the southeastern 

 portion of the United States and is unique in having 

 three yellow bands on the upper shell. The Yellow- 

 Necked Mud Turtle, C. flavescens, looks much like C. 

 pennsylvanicum and differs from that species in the 

 structure of the plastron. The sides of the neck are 

 generally bright lemon-yellow and the carapace ruddy 

 brown or dull yellowish. The range is from Arkansas 

 and Texas to Arizona. 



The Arizona Mud Turtle, Cinosternum henrici, has 

 a shell six inches long when adult. It is the largest of 

 those species found in the United States. By the very 

 flat bridge of the plastron, the under shell looking as if 

 it had been crushed in, this turtle appeals strongly to 

 the Mexican and Central American species. Both lobes 

 of the plastron close tightly, affording complete protec- 

 tion to the fleshy parts. 



In the red, muddy waters of the Colorado River this 

 turtle is common enough ; in currents that are swift and 



