186 Illinois State Laboratory of Natural History. 



The Illinois example, a large, finely-developed one, is abnormal 

 in the possession of a pair of symmetrical supernumerary mar- 

 ginal plates, one on each side of the nuchal plate, making 

 thirteen for each side and twenty-six in all. The serrated 

 mandible will distinguish the species from the P. hieroglyphica, 

 which also occurs at Mt. Carmel. 



Not mentioned in Dr. Jordan's Manual of Vertebrates. 



Malacoclemmys lesueuri. Gray. 



Very abundant in all our rivers, where it is known as the 

 mud turtle. The head of this turtle is rather small, and the 

 jaws are narrow compared with those of the next species. It may 

 always be distinguished from M. f/eographicus by a comma- 

 shaped yellow spot behind each eye. In some examples these 

 may be isolated, but in that case their transverse position is 

 characteristic. There is no tympanal stripe like that of the next 

 species. The dorsal plates are sometimes said to be imbricated, 

 but this is hardly exact, since the sutures between the plates are 

 always visible. The food of examples taken from bottom-land 

 pools at Quincy in 1888, consisted largely of the bulbs of a 

 sedge which Prof. T. J. Burrill thinks is Cyperus phyniafodes. 

 Occasional remains of moUusks and crayfish were also noted 

 in stomachs. 



Malacoclemmys geographiciis, LeS. 



Equally common with the preceding and frequenting the 

 same waters. Very different from M. lesueuri when adult, and 

 easily distinguished at all stages. The head of fully grown 

 examples is as large as that of snapping turtles of the same 

 size. The alveolar surfaces of the jaws are greatly expanded, 

 those of the upper jaw forming elevated tables into which the 

 palatine bones enter largely, and which have sharp inner mar- 

 gins which almost meet at the middle line. The characteristic 

 marks are a spot of greenish yellow behind each eye, which is 

 isolated and directed longitudinally, and a stripe of the same 

 color which originates on the tympiinum and extends down- 

 wards, then backwards, upon the neck. The great expansion of 

 the jaws is related to the food habits. An exaininafiou of 

 numerous stomachs shows it to feed upon uiollusks. 



