68 A YEAR OF COSTA RICAN NATURAL HISTORY 



continuous groove parallel to the suture where the wing- 

 covers meet and less than a sixteenth of an inch distant from 

 it. The head in both sexes is roughened and pitted and 

 bears two small projections too low to be called horns. The 

 male has three great horns on his prothorax; the female has 

 one very low pointed tubercle in the place of the front horn 

 of the male, and still less to represent the two lateral horns. 

 Much speculation has been indulged in as to the use of 

 these horns. Darwin (1871), chiefly from lack of evidence 

 as to any function, came to "The conclusion that the horns 

 have been acquired as ornaments." We have been able to 

 find no recorded observations on the uses to which the horns 

 are put in any of the Costa Rican species just described, 

 and very few for allied kinds throughout the world. Such 

 as we have brought together are as follows: Mr. G. E. 

 Murrell quoted by Lintner (1889) observed many Dynastes 

 tityus on ash-trees at Cofi^e, Virginia, "never using their 

 horns, so far as I can see, except for fighting." Dr. F. 

 Ohaus (191 1) "was able to observe in Megasoma hector^ a 

 few specimens of which he found near Petropolis, Brazil, 

 that the beetle uses its cephalic horn as a good weapon, with 

 which it can pinch hard, . . . the South American Dynas- 

 tids used this organ chiefly as a weapon." Dr. Albert L. 

 Bennett (1899), ^ho observed Goliathus druryi in German 

 West Africa and in French Congo, says: "the male beetles 

 use their cephalic horns in fighting with one another, as well 

 as for puncturing the bark of vines in order to bring about a 

 flow of the sap upon which they feed." Mr. J. Doll (1885) 

 found, in Hell's Caiion, Colorado, a Dynastes which was 

 thought by Dr. G. H. Horn to be D. granti. Doll says: 

 "They are always found near the tips of branches [of the 

 mountain ash], where by means of their projecting thoracic 

 horn they scrape through the soft bark to cause a flow of 

 sap which is very sweet, and of this consists their food." 



