84. HYDROMORPHrS. 85. DIMADES. 185 



contact with the anterior chin-shields, which are longer than the 

 posterior. Scales in 15 rows. Ventrals 141-149 ; anal divided ; 

 subcaudals 60-65. Dark brown above, with five blackish longi- 

 tudinal lines ; a more or less distinct yellowish collar ; lateral scales 

 lighter in the centre ; labials yellowish, spotted with black ; lower 

 parts uniform whitish. 



Total length 290 millira. ; tail 77. 



Costa Rica. 



a-b. S (V. 149, 141 ; C. 05, 60). Cartago, Costa Rica. (Types.) 



84. HYDROMORPHUS. 



Ilydromorphus, Peters, Mon. Beii. Ac. 1859, p. 276. 



Maxillary short, with 14 teeth, which gradually increase in length 

 to the last ; mandibular teeth subequal. Head scarcely distinct 

 from neck ; eye very small, with round pupil ; a single prefrontal ; 

 nostril directed upwards, in a single shield ; loreal entering the 

 eye. Body rather elongate, cylindrical ; scales smooth, in 17 rows ; 

 ventrals rounded. Tail short ; subcaudals in two rows. 



Central America. 



1. Hydi-omorphus concolor. 



Hydromorphus concolor, Peters, I. c. p. 277, pi. — . fig. 3. 



Head much depressed, with broadly rounded snout. Nostrils 

 directed upwards, the nasals separated by a pair of very small 

 internasals ; prefrontal twice as broad as long ; frontal slightly 

 longer than broad, as long as its distance from the rostral, much 

 shorter than the parietals ; loreal twice as long as deep ; a small 

 prasocular between the supraocular and the loreal ; two postoculars ; 

 temporals 1+2; six upper labials, third bordering the eye ; four 

 lower labials in contact with the anterior chin-shields ; posterior 

 chin-shields small. Scales in 17 rows. Ventrals 175 ; anal divided; 

 subcaudals 31. Dark greyish brown above : sides and lower parts 

 paler, the scales and shields being partly yellowish. 



Total length 850 millim. ; tail 86. 



Costa Rica. 



85. LIMADES. 



Pseudoeryx, part., Fitzing. N. Class. Rept. p. 29 (1826). 

 llelicops, part., Wagler, Syst. Atnph. p. 170 (1830). 

 llomalopsis, part., Schleg. Phys. 8erp. ii. p. 297 (1837). 

 Dimades, part.. Gray, Zool. Misc. p. 65 (1842). 

 Dimades, Gray, Cat. Sn. p. 76 (1849). 



Colopisma, part., Dum. ^ Bibr. Erp. Gen. vii. p. 336 (1854) ; Jan, 

 Arch. Zool. Anat. Phys. iii. 1865, p. 241. 



Maxillary teeth 15 to 17, gradually increasing in size ; man- 

 dibular teeth subequal. Head small, not distinct from neck ; eye 

 rather small, with round pupil ; nostril directed upwards, in a semi- 

 divided nasal ; a single internasal ; no loreal. Body cylindrical. 



