74 THE DIFFERENCES BETWEEN 



there is a spot on each side of the head behind the eye and, 

 very generally, at least, only one. 



The statements with reference to the keel of the cara- 

 pace are right for adults. Excepting reference made to 

 the keels there is nothing in the description which follows 

 that will enable anyone to distinguish the species. 



The statement concerning a yellow spot before and an- 

 other behind the ear in M. lesueuri was, I suspect, drawn 

 from De Kay's figure. 



The synopsis of reptilia by Messrs. Davis and Rice 

 (Bull., HI, 111. State Lab. Nat. Hist., 1883) introduces the 

 expression " spoon-shaped dilation of the extremity of the 

 lower jaw" as a character separating the two inland spe- 

 cies from the east coast turtle, M. palustris. The ex- 

 pression does not seem to me to fit either of the fresh 

 water species closely, and I have never known a student 

 using a synopsis or description in which the expression was 

 employed to place either of the turtles in the genus Mala- 

 coclemmys. The mandible of adult M. geographicus is 

 greatly expanded, not especially at the tip, but as a whole ; 

 and in this respect it is approached very much more closely 

 by the east coast species than by M. lesueuri. In the last- 

 named species the mandible is not noticeably expanded 

 and certainly is no more spoon-shaped than the mandible 

 of species of Pseudemys. If the expression was to have 

 been used at all, it should have been for the purpose of 

 separating M. geographicus and M. palustris on the one 

 hand from M. lesueuri on the other. The two former are 

 not so closely related as are the two inland species, but so 

 far as this one character is concerned are certainly more 

 alike. The statement that the dorsal plates of M. lesueuri 

 are imbricated while those of M. geographicus arc not, 

 is not strictly true. The plates are not imbricated in the 

 proper sense of the word in either species. 



