1885.] *^"'' [Cope. 



shorter tail, which is one-third the length in the E. saekeni, in the eight 

 superior labials, and in the generally stouter proportions, as well as in the 

 red lips. 



PSEUDEMTS ORNATA Bell. 



ClNOSTERNUM LEUCOSTOMUM Dum. 18,910-11-12-13. 



This is a variable species. Two specimens from Tehuantepec from Su- 

 michrast (Nos. 141 and 76, Coll. Sumichrast), both males, are rather wider 

 and more depressed than are specimens from Tobasco and Cozumel. The 

 posterior lobe of the plastron expands abruptly at the base on each side. 

 In nine specimens from Tobasco from Dr. Berendt, the posterior lobe dis- 

 plays its lateral convexity behind the base on each side ; the anterior lobe 

 is more accuminately rounded, and the shell is less depressed. None of 

 these specimens Jiave axillary scuta. Four specimens from Cozemel are in- 

 termediate in the form of the lobes of the plastron The carapace is rather 

 elevated, and exhibits traces of those keels as do the others. 



The species of this genus which inhabit Mexico, with which I am 

 acquainted, are the tollowing : 



I. Carapace with three distinct longitudinal keels above. 



Carapace flat, depressed '.C. scorpioides Wagl. 



Carapace compressed, elevated C shavianum* Bell. 



II. Carapace without distinct keels. 



a. Axillary scuta rudimental or wanting and not reaching the Ingui- 

 nals. Plastron entire posteriorly. 



Inguinal plate mostly behind posterior hinge ; gular very small 



C. brevigulare\ Cope. 



Inguinal plate large, in front of posterior hinge ; gular large 



C. leucostomum Dum. 



* C. mexicanum Lee. C cruentatum A. Dum. 



t C. leucostmnum " Dum." Cope. Journal Academy Phila., 187.5, p. 153. Two 

 specimens from Costa Rica represent this species, which is clearly distinct from 

 the C. leucostomum. Besides the two characters above mentioned, it diflfers 

 from the C. leucostomum in the sudden enlargement of the penultimate marginal 

 scute as compared with the antepenult; the former is much elevated, the latter 

 is very narrow in the horizonta^l direction. In C. leucostomum, the size of these 

 plates is graduated. The long diameter of the gular scute is less than two-fifths 

 the length of the anterior lobe of the plastron ; it is from one-half to two-thirds 

 the same dimension in the C. leucostomum,. The free lobes of the plastron are 

 relatively larger than in C leucostomum. The fixed portion is .75 of the anterior, 

 and .66 of the posterior lobe; in C. leucostomum it is nearly equal to the anterior, 

 and is .75 of the posterior. It also difTers from the same species, in having no 

 trace of median or lateral keels of the carapace. Of the two specimens, one,, 

 probably a male, is a little more elevated and a little narrower than the other. 

 The measurements of the two are cf : length M. .144; width, .089; of the $ : 

 length, .127; width, .083. The axillary plate, as in C leucostomum, is mostly in 

 front of the axilla. The inguinal plate on the other hand is much shorter an- 

 teriorly, where it narrows to a point, and extends even further posterior to the 

 posterior hinge-line, which is not tlie case in C. leucostomum. 



From the Tierra Calienteof Costa Rica at Sipurio, on the east coast. Discov- 

 ered by Dr. Wm. M. Gabb. 



