. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. 32 SEXUAL SELECTION. [Part II. rived at maturity, at which age the middle appendage is sometimes twice as long as the head. Most of the species likewise have a low crest running along the neck ; and this is much more developed in the full-grown males than in the females or young There are other and much more remarkable differences between the sexes of certain lizards. The male of Cerato- phora aspera bears on the extremit
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings. 32 SEXUAL SELECTION. [Part II. rived at maturity, at which age the middle appendage is sometimes twice as long as the head. Most of the species likewise have a low crest running along the neck ; and this is much more developed in the full-grown males than in the females or young There are other and much more remarkable differences between the sexes of certain lizards. The male of Cerato- phora aspera bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, and apparently capable of erection : in the female it is quite rudimental. In a second species of the same genus a terminal scale forms a minute horn on the summit of the flexible appendage; and in a third species (C. Stoddartii, Fig. 34), the whole append- age is converted into a horn, which is usually of a white color, 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 lengt h, but is of quite minute size in the female and in the young. These appendages, as Dr. Gtlnther lias remarked to me, may be com- pared with the combs of galli- naceous birds, and apparently serve as ornaments. In the genus Chamadeon we come to the climax of dif- ference between the sexes. The upper part of the skull of the male C. bifurcm (Fig. 35), an inhabitant of Mada- M All these statements and quotations, in regard to Cophotis, Sitana, and Draco, as well as the following facts in regard to Ccratophora, are taken from Dr. Gunther's magnificent work on the 1 Reptiles of British India,' Ray Soc. 1864, pp. 122, 130, Fig. $4.—Ceratophora Stoddartii. Upper flpure, male ; lower figure, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colora
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