362 SEXUAL SELECTION [Part II. 



with Lamelli corns), or in having none at all. Now, if a 

 new species of deer or sheep were discovered with the 

 female bearing distinct rudiments of horns, while the 

 head of the male was absolutely smooth, we should have 

 a case like that of Onitis furcifer. 



In this case the old belief of rudiments having been 

 created to complete the scheme of Nature is so far from 

 holding good, that all ordinary rules are completely 

 broken through. The view which seems the most proba- 

 ble is that some early progenitor of Onitis acquired, like 

 other Lamellicorns, horns on the head and thorax, and then 

 transferred them, in a rudimentary condition, as with so 

 many existing species, to the female, by whom they have 

 ever since been retained. The subsequent loss of the 

 horns by the male may have resulted through the prin- 

 ciple of compensation from the development of the pro- 

 jections on the lower surface, while the female has not 

 been thus affected, as she is not furnished with these pro- 

 jections, and consequently has retained the rudiments of 

 the horns on the upper surface. Although this view is 

 supported by the case of Bledius immediately to be given, 

 yet the projections on the lower surface differ greatly in 

 structure and development in the males of the several spe- 

 cies of Onitis, and are even rudimentary in some; never- 

 theless the upper surface in all these species is quite desti- 

 tute of horns. As secondary sexual characters are so emi- 

 nently variable, it is possible that the projections on the 

 lower surface may have been first acquired by some pro- 

 genitor of Onitis and produced their effect through com 

 pensation, and then have been in certain cases almost 

 completely lost. 



All the cases hitherto given refer to the Lamellicorns, 

 but the remains of some few other beetles, belonging to 

 two widely-distinct groups, namely, the Curculionidse and 

 kitaphylinidi©, are furnished with horns — in the former on 



