FISHES. 385 



filaments can be useful in any ordinary way to the males 

 alone. In that strange monster, the Chimcera monstrosa, 

 the male has a hook-shaped bone on the top of the head, 

 directed forward, with its end rounded and covered with 

 sharp spines ; in the female " this crown is altogether 

 absent," but what its use may be to the male is utterly 

 unknown.* 



The structures as yet referred to are permanent in the 

 male after he has arrived at maturity; but with some Blen- 

 nies, and in another allied genus, f a crest is developed on 

 the head of the male only during the breeding season, and 

 the body at the same time becomes more brightly colored. 

 There can be little doubt that this crest serves as a tem- 

 porary sexual ornament, for the female does not exhibit a 

 trace of it. In other species of the same genus both sexes 

 possess a crest, and in at least one species neither sex is 

 thus provided. In many of the Chromidse, for instance in 

 Geophagus and especially in Cichla, the males, as I hear 

 from Prof. Agassiz, J have a conspicuous protuberance on 

 the forehead which is wholly wanting in the females and 

 in the young males. Prof. Agassiz adds: "I have often 

 observed these fishes at the time of spawning when the 

 protuberance is largest, and at other seasons when it is 

 totally wanting, and the two sexes show no difference 

 whatever in the outline of the profile of the head. I 

 never could ascertain that it subserves any special func- 

 tion, and the Indians on the Amazon know nothing about 

 its use." These protuberances resemble in their periodical 

 appearance the fleshy carbuncles on the heads of certain 

 birds; but whether they serve as ornaments must remain at 

 present doubtful. 



I hear from Prof. Agassiz and Dr. Giinther that the 

 males of those fishes which differ permanently in color 

 from the females often become more brilliant during 

 the breeding season. This is likewise the case with a 

 multitude of fishes, the sexes of which are identical in 



*P. Buckland in "Land and Water," July, 1868, p. 377, with a 

 figure. Many other cases could be added of structures peculiar to 

 the male, of which the uses are not known. 



f Dr. Giinther, " Catalogue of Fishes," vol. iii, pp. 221 and 240. 



j Sea also " A Journey iii Brazil," by Prof, and Mrs. Agassiz, 1868, 

 p. 220. 



