102 BULLETIN" 15 4, UNITED STATES NATIONAL MUSEUM 



coloration becomes modified, and tlie t^-pe of postaiitebrachial scala- 

 tion is changed. In fact numerous striking combinations may be 

 found. Thus, man_y local phases are produced and it is little wonder 

 that certain workers, disregarding or overlooking the trivial nature 

 of certain of these variants (with especial reference to their remark- 

 able instabilitv" and frecpient geographic repetition) have found lit 

 to give them taxonomic designations. 



During the period of its development, gularis goes through an in- 

 tricate series of pattern stages, and while there is considerable indi- 

 vidual variation, the evolution is in all cases essentially the same. 

 The young are often unspotted, and in such, the appearance of spots 

 in the lateral fields may be expected sooner or later. In certain in- 

 dividuals and regions spotting is retarded more than in others and 

 at times the spotted phase is transformed into a tiger-barred one 

 by the spreading of the spots to form crossbars with the stripes 

 above and below them. This is often accompanied by a tendency 

 for the dark ground color to encroach upon the longitudinal light 

 stripes and to unite across them. Thus the whole aspect of the pat- 

 tern ma}" be changed, the emphasis being transferred from the longi- 

 tudinal to the transverse. At other times the lines break into spots 

 and disappear as longitudinal elements. This is accompanied by 

 profuse spotting in the interspaces and the assumption of a dull, 

 uniform ground color. The barred phase has been described as 

 scalaris and is found in both gularis and ferplexus^ while the spotted 

 j)hase has been called hocourtii. When series are examined it be- 

 comes apparent that the presence or absence of lines, spots, or cross- 

 bars in a specimen is not a reliable diagnostic feature. 



As indicated above, the phases and variations of gularis have 

 given rise to a large number of taxonomic designations. Since the 

 color evolution seems essentially the same in all regions, treatment 

 of the described forms under phase or variation seems unnecessary. 

 Therefore, they are placed under five more or less arbitrary heads 

 as follows: I, the forms from Texas and northeastern Mexico; II, 

 the forms of Chihuahua ; III, the " communis " group ; IV, the " mex- 

 icanus " group ; and V, the forms from uncertain localities. 



I. The forms from Texas and northeastern Mexico are as follows : 

 Gularis, inornmtus, guttatus, sericeus, semifasciatus, and ineeM. The 

 fii'st of these, gularis, was described from Texas. The types are 

 typical of what is here considered as gularis, having enlarged scutes 

 on the back of the forearm, a ventral patch of dark bluish and a 

 widened middorsal area. The two specimens described as inornatus 

 by Baird (1858) are from Nuevo Leon and differ from gularis in 

 the absence of dorsal markings. An examination of the cotypes 

 shows that they are both small (about 55 mm. from snout to anus) 

 and that thcv are blackish and badlv faded. As remarked bv Gadow 



