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Show 34 SEXUAL SELECTION. PAnT II. There are other and much more remarkal>le differences between the sexes of certain lizards. The male of Ceratophora aspera bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, ancl apparently capal>le of erection: in the female it is quite rudimental. In a ser.ond species of the same genus a terminal scale forms a minute horn on tl1e summit of the flexible appendage ; and in a third species (a. Stoclclartii, fig. 34) the whole appendage is converted into a horn, which is usually of a white colonr, but assumes a purplish tint when the animal is excited. In the adult male of this latter species the horn is half an inch in length, but is of quite minute size in the female and in the young. These appendages, as Dr. Gunther has remarked to me, mn.y be compared with the combs of Fig. 3-1. Ccrntophnra Stoddt~rlii. Upper gallinaceOUS birds, and appafigure, male; lower figure, female. ently serve as ornaments. In the genus Cbam::cleon we come to the climax of difference between the sexes. The upper part of the skull of the male C. bif~wcus (fig. 35), an inhabitant of Madagascar, is produced into two great, solid, bony projections, covered with scales like the rest of the bead; and of thil::i wonderful modification of structure the female exhibits only a rudiment. Again, in Chammleon Owenii (fig. 3G), from the vVest Coast of Africa, the male bears t11ken from Dr. Giinther's mn~nificent work on the' Reptiles of British Indio.,' Rn.y Soc. 18G1, p. 122, 130, 135. CuAr. xrr. REPTILES. 35 on his snout and :t: . 1 d 1 . tl -" 1 ore lea t 1ree curwus horns of which an1 0 l.e ma e has not a t race. rT hese horns ' consist of excrescence of b d . .r 0 • . one covere with a smooth sheath 11 tmmg part of th 1 · ' so that the a . e g~nen~ mteguments of the body, y re lclentwal m structure with those of a Fig. JG. Chamrelcon bifurcus. Upper figure, mule; lower figure, female. ~~~l,t~~;:· ~::~~e~·li~eei~t~~hornccl r~1minant. Although the two great prolo t' much m appearance from n aa IOns of the 1 11 · 0. · we can hardly doubtbthat the . ~ m m . bifurcus, purpose in tl Y ser' e the same general le economy of these two animals. The D 2 |