NATURAL SCIENCES OF PHILADELPHIA. 27 



pace with more nearly parallel sides, with three stronger or more 

 elevated keels above. It differs in the possession of an emargi- 

 nation between the anal scuta. The plastron differs in the shorter 

 and less acuminate posterior lobe with shorter bridge. The 

 femoral scuta extend behind the abdominals on the bridge, while 

 the latter cover its entire width in G. pictus. The infra-marginal 

 plates are longer than wide in this species; in G. pictus they are 

 transvei'se. The tail of this species exhibits the usual four rows 

 of tubercles, while in G. seve?nts it is smooth. The head is nar- 

 rower in G. pictus, and the colors more varied. Thus the top of 

 the head is pale spotted on a brown ground, the jaws are yellow 

 with brown cross-bands; a 3 r ellowish band extends from their 

 angle over the tympanum to the side of the neck. Carapace yel- 

 lowish-brown with a dark brown spot on the posterior part of 

 each scutum ; limbs brown above ; plastron yellow with a brown 

 spot on each scutum. Length of carapace, .136 m. 



From Vera Paz. 



This species is beautifully figured by Bocourt, as above cited. 



CLAUDIUS MEGALOCEPHALUS, Boc. 



Ann. Sci. Nat. Zool., 18G8, X. p. 122. G. angustatus, "Cope," Bocourt, 

 Miss. Sci. Mex. Zool. Rept, p. 20, tab. iv. 



This species and the G. angustatus constitute the typical and 

 smaller forms of the genus, distinguished by the very slender 

 bridge of the plastron and single inguinal or intermarginal. The 

 present animal, after being described as distinct by Bocourt, was 

 subsequently referred to the longer described C. angustatus, but I 

 am disposed to regard his first conclusion as the more correct, 

 having received from Sumichrast a second specimen of the latter, 

 which confirm its characters. 



In C. megalocep>halus, according to Bocourt, the head is very 

 wide and the muzzle short, with hooked beak. Its upper surface 

 does not display the oval horny scute seen in G. angustatus, and 

 though there is a convexity of the edge of the maxilla below the 

 front of the orbit, it is not an acute tooth as in the type of C. 

 angustatus. This appearance may perhaps be due to age. 



The carapace is three keeled above, the median keel fissured in 

 its length. The keels traverse all the costal and vertebral scuta, 

 except perhaps the last vertebral. The plastron is rather wide 

 with the anterior lobe a little longer; neither lobe is much nar- 

 1872.] 



