310 Du. II. GADow OX EvoLunox [Mar. 20, 



thumb procedure, applied to 86 specimens, gives the following- 

 result : — 



Number of femoral rows ... 4 to 5 '5 6 6-7 7 8 ,' Mean number 



of rows. 

 Soutbern Oaxaca |r 3 10 1 2 1 j fi-O 



Coast of S. Luis 'I | 2 10 8 1 5-4 



Tierra Colorada -Z I ... 1 17 2 2 ... 6-0 



c 



Kio Balsas ^L H 1 14 ••■ > 6-5 



2 14 46 5 18 1 specimens. 



This tabulation is naturally very imperfect, not to say crude, 

 but the results will not be altei'ed when we throw the intermediate 

 or douVjtful cases of 6 to 7 rows either into the column with 6 or 

 into that with 7 complete rows. There were, for instance, amongst 

 the Oaxaca specimens four with 5 or 6 rows, but amongst those 

 of Guerrero only two such doubtful cases. The fact remains, that, 

 if we take Tierra Colorada as normal, those further south tend to 

 possess fewer femoi'al scales, whilst those fui'ther iioi-th, at Rio 

 Balsas, have decidedly more scales. This does not seem to be the 

 result of mere chance, because, as we shall see, the Balsas speci- 

 mens are I'emarkable for other features, although they are not 

 peculiar to them. Amongst the specimens from the State of 

 Oaxaca. no difierence whatever can be discerned with reference to 

 their habitat nearer to or further away from the coast. 



At any rate the amplitude is considerable, the extiemes being- 

 two specimens with an imperfect 5th row, and one with 8 rows ; 

 the latter specimen, from Tequesixtlan, is in eveiy other respect 

 a typical C. de2)pei. 



Inner side of tibia pi"otected by 2, 2^, or 3 complete rows of 

 enlarged scutes. 



Preanal region. — As a rule there are 3 lai-ge scales which foi'm 

 a triangle, with two at the base and a third of equal size on the 

 top, bvit sometimes a fourth scale forms the apex ; or the tv.o 

 basal scales are small, whilst the third is correspondingly enlarged. 

 In the majority the whole cluster is separated from the ventrals 

 by a very short isthmus, sometimes so short that the clustei- and 

 the ventrals almost touch each other. The isthmus itself is mostly 

 covered with very small scales, and when these are larger the}' 

 are fewer in numbers. The whole character is worthless. 



Femoral pores. — The number of pores frequently differs on the 

 right and left side by one, rarely by two, in the same individual. 

 There is no preference for one side. The smaller number in these 

 cases of asymmetiy is always due to one or moi-e pores i-emaining 

 undeveloped at the proximal, or more frequently at the distal end 

 of the series. For comparison, the higher number should there- 

 fore alwaj'S be taken. The amplitude of individual vai'iation is 

 considerable, when Ave recollect that these pores cori-espond in 

 numbers with transverse rows of scales. But unfortunately the 



