192 Heredity. 



that they have originated in one sex rather than in the 

 other. The organs are essentially alike in structure, 

 whether they are confined to the male or are present in 

 both sexes; and as we have good reason for believing, in 

 the first case, that they have originated in males, and 

 no reason for doubting that they have so originated in 

 the second case, the conclusion that they all have had a 

 male origin certainly has a great probability in its favor. 

 The great diversity of the males of allied species, as 

 compared with the females, is well shown in those beetles 

 where the males, and not the females, have great horns 

 rising from various parts of the body, as from the head, 

 thorax, clypeus, or the under surface of the body. 

 Darwin gives the following account of these structures: 

 *' These horns, in the great family of Lamellicorns, resem- 

 ble those of various quadrupeds, such as stags, rhi- 

 noceroses, etc., and are wonderful both from their size 

 and diversified shapes. The females generally exhibit 

 rudiments of the horns, in the form of small knobs or 

 ridges, but some are destitute of even a rudiment, while 

 in a few others they are almost as well developed in the 

 female as they are in the male. In almost all cases the 

 liorns are remarlcahle from their excessive variahility; 

 so that a graduated series can be formed, from the most 

 highly developed males to others so degenerate that they 

 can hardly be distinguished from the females. The ex- 

 traordinary size of the horns, and their widely different 

 structure in closely allied forms, indicate that they have 

 been formed for some important purpose, but their ex- 

 cessive variability in the males of the same species leads 

 to the inference that this purpose cannot be of a definite 

 nature. They do not show evidence of friction as 

 they would if used for ordinary work. They are not 

 usually sharp, and do not seem well adapted for defence. 



