130 THE WASATCH AM) liKlDCiKK FAUN^. 



Shell rorv thick, little nnhed ; vertebral scuta wide; sutures of plas- 



trou straight ; its lip nurrow E. shaughnaigiana. 



Shell thiu, little arched; vertebral scuta wide; lip of plastron very 



wide . E. latilahiata. 



Shell thin coossified, much arched above ; sutures of plastron irreg- 

 ular ; vertebral scuta longer than in other species E. haydeni. 



II. Axillary and inguinal buttresses very i)roinineut. 



Shell thin, carapace convex, not keeled ; scutal sutures not deep E. septaria. 



The distribution of these species is as follows : 



Wasatch, Wyoming — £. tastudinea, E. evthneta, E. megaulax; New- 

 Mexico — E. lativertehralis. 



Bridger, Wyoming — E. pohjcypha, E. terrestris, E. tvyomingensis, E. 

 shaughnessiana, E. latilahiata, E. haydeni. 



Washakie — E. septaria. 



It is true that in many Emydidce the young stages are characterized by 

 a dorsal carina and greater width of the dermal scutal grooves. Dr. Leidy 

 has suggested * that the immature stages of Emys wyomingensis are repre- 

 sented by certain keeled specimens in his possession ; and also states that 

 the mesosternal bone is more elongate in such specimens than in the larger 

 ones. I have suspected that the forms I have named, Emys pohjcypha and 

 E. terrestris, might be the young of E. shaughnessiana and E. wyomingensis 

 respectively, but I have not identified them on account of the lack of spec- 

 imens displaying intermediate characters, and also because of the shorter 

 gular scuta of E. terrestris. If the mesosternal bone is longer in the young 

 than in the adult E. wyomingensis, it should bear more rather than less of 

 the gular scuta. The Emys megaulax of the Wasatch beds presents the 

 characters of immaturity in the low median keel and the deep and wide 

 sutural grooves. It is much larger than either of the two species just 

 named, and its bones are stout. It cannot be the young of its cotemporary 

 E. euthneta, for that does not exceed it in size. I have parts of several 

 individuals of both for comparison. It is true that in all three of the spe- 

 cies presenting these characters of immaturity, the shells are, so far as 

 known, without fontanelles, and that in the smallest, E. polycypha, the ver- 

 tebral 1 nines are relatively the thickest. 



• Report U. S. Geol. Surv., i, p. 148. 



