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Show 360 DR. H. GADOW ON EVOLUTION [Mar. 20, large-scaled collar of the var. balsas and of G. communis occidentalis. Humerus mostly with 4 large and about as many smaller rows of scales, some of which pass gradually on the elbow into those of the posterior side of the forearm. Forearm (text-fig. 63 A - D ; 61 C).-Here prevails considerable variation. It is rarely covered entirely with granules, several rows being enlarged, although sometimes but slightly ; as a rule more obviously so that a cluster, or several rows of large polygones, are present; only in one specimen, the smallest of the types, is the one long row of large, transverse scutes in the var. typica. But in the var. bcdsas large scutes are much more common. The great variability, even in specimens from the same locality, is shown in the table, p. 362. Front of forearm (text-fig. 61 A, B, D).-Mostly with three complete rows of plates, rarely with only two large rows, sometimes with a smaller fourth lateral row. Attention may be drawn to the peculiar arrangement (text-fig. 61 I) which was observed in a specimen from Cuernavaca and one from the southern slope of the Cajones ridge, a very good illustration of the fact that in the kaleidoscopic changes of this scutellation exactly the same arrangement may be hit upon "accidentally " in widely separated specimens. Front of tibia with 3 to 4 rows. Femur mostly with 7 rows, 3 of which extend to the knee, as is the case in C. sexlineatus and C. deppei. Femoral pores mostly from 16-20; cases of 23 or 24 being quite exceptional. The males reach a great size ; specimens of 120 m m . being quite common. The largest, of 132 mm., from Totolapan, is one of the record specimens of Cnemidophori, surpassed only by two specimens of C. communis australis from Cuicatlan, likewise in the State of Oaxaca. CNEMIDOPHORUS MEXICANUS, var. TYPICA. Material examined :- I. The three type-specimens in the Berlin Museum, collected by Uhde, and supposed to be from the neighbourhood of the town of Oaxaca. II. 16 specimens collected by myself a few miles to the west of Oaxaca town on oper, rather barren terrain, or on the slopes of stony ravines with scanty scrub. III. 4 specim' is at Totolapan, a similar terrain, near the southern foot of the Mexican plateau, in the Tierra caliente. Unfortunately all the type-specimens are young. They happen to agree with each other, and differ from those collected by myself by decidedly larger scutes on the posterior side of the forearm. Coloration.- Under parts mostly uniform pale yellowish white, with a reddish tinge on the hind limbs and on the throat, while |