274 Trans. Acad. Sci. of St Louis. 



Preocular. a. Rostral.— Fig. 7. Posterior dorsal vertebra of LioJietero- 

 don riiadagascaricnsis. b. Lower view. c. Side view. a. Back view, 

 h. Hypapophyses. (Boulenger.) — Fig. 8. Posterior dorsal vertebra of 

 Heterodon simus. No hypapophyses or haemal processes. (Boulenger.) 



Plate XXII. — Fig. 1. Dorsal view of shell (carapace) of Ghrysemys 

 marginata Agass. d. Dorsal plates, c. Costal plates, m. Marginal 

 plates, n. Nuchal plate.— Fig. 2. Ventral view of shell (plastron) of 

 Chrysemys marginata. g. Gular plate, h. Humeral plate, p. Pectoral 

 plate, a. Abdominal plate. Pr. Pre-anal plate, an. Anal plate, ax. 

 Axillar plate. Ing. Inguinal plate. — Figs. 3-6. Skulls of Terrapene, 

 showing modifications of the zygomatic arch in different species. — 

 Fig. 3. Skull of Terrapene major, a. Post frontal, b. Quadrato-jugal. 

 c. Jugal. — Fig. 4. Skull of Terrapene Carolina. — Fig. 5. Skull of Ter- 

 rapene kinosternoides. — Fig. 6. Skull of Terrapene ornata. 



Plate XXIII. — Young Chrysemys, all about the same age. — Fig. 1. 

 Chrysemys picta Schn. Fig. 2. Chrysemys marginata Agass. — Fig. 3. 

 Chrysemys treleasei Hurter. — Fig. 4. Chrysemys belli Gray. 



Plate XXIV. — Adult specimens of Chrysemys treleasei n. s. — Top 

 Fig. Dorsal view. — Middle Fig. Side view. — ^Lower Fig. Ventral 

 view. 



Issued July 28, 1911. 



