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Show 352 DR. n. GADOW ON EVOLUTION [Mar. 20, which are typically at home in Mexico extend far into Central America, occasionally cropping up very locally-a sporadic distribution most likely due to our want of data. Two specimens {Brit. Mus.) from the Island of Cozumel, east coast of Yucatan, have to be referred to C. communis copei until more Cnemidophori * from the huge peninsula of Yucatan have been collected. There are 4 supraoculars. The collar-scales form complete rows, but are distinctly small, as in the Cuicatlan specimens, with which those of Cozumel agree also in the number of femoral rows and pores. The large polygones on the forearm agree with those of San Domingo and Colima. There are 7 pale stripes on the back, all narrow and still complete, but each stripe contains small white specks, and similar small specks are numerous in the fields, on the rump and on the thighs. It is noteworthy that several of the upper labials are denticulated, exactly as in the C. deppei specimens from the same island ! CNEMIDOPHORUS COMMUNIS AUSTRALIS. (Text-figs. 62 C, D; 64C,D; 65 F; 79B,C.) Diagnosis : like C. copei, but with entirely granular forearm. Seven specimens collected by Dr. Meek at Lagunas, a station a little further east than San Domingo, still on the western slope of the Isthmus.-They agree with the typical C. c. copei in the large number of femoral pores, of femoral and humeral rows, composition of the large-scaled collar, the large average size of the adults, and by the colour-pattern; but they differ without exception by the complete absence of any scutes or enlarged polygones on the posterior side of the forearm. It is to be remembered that this character is not very reliable in Southern Mexico; see certain specimens of G. mexicanus from Cuautla, Sojutla, and Oaxaca, and of C. communis occidentalis from Puebla. In some of the 7 specimens the 4th supraocular is very small. The evolution of the colour-pattern seems to proceed as follows :- In the youngest specimens the first and second pairs of stripes are still white and complete, quite conspicuous ; the third stripe is becoming faint and breaks up into white spots on the lower back and rump. Fields I. and II. are still black, without any spots. Thighs above still without specks; behind reddish, with spots or traces of a pale stripe. In specimen 98 mm., stripes 3 and 2 are fading or becoming grey from the neck backwards, neck and shoulders becoming grey. Small whitish spots appear in one or two rows in fields I. and II. * C angusticeps Cope, Proc. A m . Phil. Soc. xvii. 1877, p. 95. The four specimens seem to be the only Cnemidophori known from " Yucatan." According to Cope they are like his C. communis, but distinguished by the very narrow parietal and interparietal plates. Four supraoculars. Edge of collar composed ot large scales. Frenocular present. Ground-colour black and fields much wider and not broken up. The stripes send off lateral processes which give the dark ground-colour a very broken character. I lelds green. Adult male ot the size of C. communis and C. guttatus. |