192 Barbour — Physignathus cocincinus and its Subspecies. 



Lateral teeth eighteen on each side. Six or seven enlarged shields along 

 each side of the throat. 



P. cocincinus mentager Gunther. 



From Siam. 



Eleven or twelve lateral teeth. Eleven enlarged shields along each side 

 of the throat. 



P. cocincinus caudicinctus subsp. nov. 



Type.— Skin of a large adult in alcohol with cleaned sknll attached. 

 Coll. Mus. Comp. Zool. No. 8852. From Laokay, Tonkin. Koyobashi, 

 collector. 



Closely related to the two preceding forms but differing as follows: 

 lateral or molardike teeth, eighteen on each side of upper jaw and fourteen 

 on each side of lower. (This rather as in P. c. cocincinus. ) A series of 

 fourteen enlarged shields along each side of throat parallel with the in- 

 fralabials. (In this respect tending toward the condition in P. c. 

 mentager. ) 



The new form is thus evidently related to both the others and as their 

 ranges probably meet and as intergrades probably occur in the boundary 

 regions of their ranges, the three forms may best be considered geographic 

 races of the one species. 



