in the Collection of the British Museum. 31 



across the chin. A large round white spot on each side of the 

 occipital region. 



A male was obtained from the collection of the late Dr. van 

 Lidth de Jeude ; it is probably from Surinam, and is 26^ inches 

 long, the tail being 9 inches. 



Leptognathus dimidiatus. 



Scales smooth, in fifteen rows, those of the vertebral series 

 not enlarged. Body much compressed, neck slender, head 

 broad and short. Eye rather large, with vertical pupil. An- 

 terior frontals short and small ; posterior frontals large, ex- 

 tending down 'on the sides of the snout, and forming the 

 antero-superior part of the orbit. Vertical with nearly parallel 

 outer edges, and with a right angle behind, shorter than the 

 occipitals. Loreal confluent with the single prgeocular ; two 

 postoculars. Eight upper labials, the fifth and sixth entering 

 the orbit. Temporals 1+2 + 3. Three pairs of chin-shields, 

 the anterior the largest, crescent-shaped, much longer than 

 broad ; the middle shorter, but still longer than broad ; the 

 posterior of about the same size as the middle, and divergent. 

 An azygos scale-like shield between the front chin-shields and 

 the minute median labial. The first pair of lower labials are 

 not joined together by a suture, being separated by the azygos 

 shield ; the five following lower labials are in contact with the 

 anterior chin-shields. Ventrals 186 ; anal entire ; subcaudals 

 98. Body and tail with broad black rings separated by whitish 

 interspaces much narrower than the rings ; there are 25 black 

 rings on the trunk and 16 on the tail. The white interspaces 

 are again each subdivided by a nan-ow black transverse line. 

 Upper parts of the head black, with small whitish spots irre- 

 gularly placed ; a pair of large whitish spots on the neck, 

 forming a kind of collar. Anterior chin-shields black. 



An adult female from Mexico (purchased) is 1 7 inches long, 

 tail 5 inches. 



Leptodira semiannulata. 



Scales smooth, in nineteen series. Ventrals 227 ; anal en- 

 tire; subcaudals 27 + a; (about one half of the tail is lost). 

 Head broad and depressed. Anterior frontals very small ; 

 loreal rather longer than deep ; anteocular single, not reaching 

 the vertical ; two postoculars. Eight upper labials, the third, 

 fourth, and fifth entering the orbit. Temporals 2 + 3 + 3. 

 Chin-shields very small. The posterior maxillary tooth long 

 and grooved. Yellowish olive ; back with about 32 brownish- 

 black transverse spots or bands, rather iri'egular in shape, and 

 separated by interspaces broader than the spots. The first 



