274 Trans. Acad. Sci. of St. Louis. 



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

 don viadagascariensis. b. Lov/er 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 Chryscmys 

 marginnta 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. Chryscmys marginata Agass. — Fig. 3. 

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



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

 Fig. Dorsal viev.'. — Middle Fig. Side view. — Lower Fig. Ventral 

 view. 



Issued July 28, 1911. 



