SNAKES. 117 



Adult : back with a broad, dark brown, anteriorly yellow-edged 

 dorsal band; sides brown, irregularly black-spotted ; belly uni- 

 form yellowish, on the sides black-spotted -, longitudinal bands 

 along the middle of belly very obsolete. 



Younger individuals : back with (quadrangular brownish -olive 

 cross bars, alternating with more irregular lateral spots; belly 

 more or less black-spotted, spots sometimes arranged in longi- 

 tudinal rows. 



a. Adult. Venezuela. From Mr. Dyson's Collection. 



b. Half-grown. Venezuela. From Mr. Dyson's Collection. 



c. d. Half-grown. Venezuela. From Mr. Dyson's Collection, 

 e. Half-grown. Berbice. Presented by Lady Essex. 



f. Half-grown : not good state. Berbice. 



g. Young : bad state. Brazil. Old Collection. 



h. Half-grown. West Indies. Presented by Colonel Reid. 

 i. Young. America. 



k. Half-grown. America. From Mr. Mather's Collection. 

 I, m. Half-grown. America. Presented by Edward Cook, Esq . 

 n. Young : bad state. America. 



o. Half-grown. America. Presented by the College of Surgeons. 

 Description.— ^?i\i\t slender ; head depressed, flat, rather 

 narrow, but distinct from neck; eye moderate. Rostral shield 

 broader than high, rounded above, reaching the surface of head ; 

 frontals moderate, subquadrangular ; vertical more than twice as 

 long as broad, with much convergent and concave outer edges, 

 and a right angle behind; occipitals moderate, rather deeply 

 forked (under a right angle), in young individuals not forked ; 

 anterior ocular raised on the surface of crown, grooved before 

 the eye, not reaching the vertical ; two posterior oculars ; super- 

 ciliary prominent, elongate ; loreal elongate, two moderate nasals ; 

 upper labials nine, fourth, fifth and sixth coming into the orbit; 

 temporal shields five or six, two elongate in front, two broader 

 ones behind, one or two small ones between. Scales smooth, 

 rhomboid, in seventeen rows ; anal bifid. Teeth equal, smooth. 



This species is one of the most interesting, on account of the 

 differences of colour in old and young individuals. We may add 

 to the above description of the colour, that some scales of the 

 front part of the brown dorsal band, occupying the whole breadth 

 of the back, are white-edged, forming together narrow white lines ; 

 upper labials yellow, above and beneath black-edged ; lower jaw, 

 chin and throat black, with a few rounded white spots. In 

 younger individuals the dorsal cross bands are very regularly 

 quadrangular-oblong, the lateral ones subquadrangular ; ground 

 colour of the throat black, but the round white spots are pre- 

 dominant. This species is named in honour of Professor W. von 



