S3 



The shields covering the lower jaw are also regularly 

 arranged. In front, corresponding to the rostral above, is a 

 single shield, the mental, and from it the lower labials go 

 backwards, edging the lip on either side. The pair of first 

 labials nearly always meet in the median line behind the 

 mental, but the other lower labials, are separated by two 

 pairs of longitudinally disposed ^e^iem^ shields one behind 

 the other. The geneials of either side are separated by a 

 tolerably deep mental groove in all but the lower types. 

 One or more pairs of scales (gular scales) usually intervene 

 between the geneials and the first ventral shield. 



The shields above described are found in most of the 

 hit^her types of snakes. Their place is sometimes filled by 

 scales especially in the lower types, but a redundancy of 

 shields is rarer ; the multiple shields may be increased or 

 diminished in number, but the intercalation of abnormal 

 shields is not often met with. Zamenis diadema and the 

 Pythonidce ofier almost the only examples of redundant 

 shields on the crown. Sub-division of shields often occurs, 

 but very rarely is the character constant ; it is usually an in- 

 dividual aberrance to be commonly found in certain species. 



The colour of the integument is generally resident in the 

 scales, although it frequently happens either that the true 

 skin partakes of the colour of the scales or that the scales 

 show between their edges the ground colour of the skin 

 beneath. This skin is usually white, but black cross-bands 

 on it are not uncommon, as also reticulated patterns in- 

 yellow, red, or pale blue. The two latter colours come 

 and go in the same manner as the colours of a turkej^'s 

 wattles, and they are often interchangeable in the same 

 individual, e. g. Tropidonotus stolatus. The scaly coat has 

 generally a ground-colour of olive brown in various shades 

 and tints. Other colours also commonly occur, black, brown, 

 yellow, green, white and more rarely red and blue. Green 



5 



