NOTES AND LITERATURE 



ICHTHYOLOGY 

 Ichthyological Notes.— One of the most valuable papers on the 

 habits of fishes is a study in sexual selection by Cora D. Reeves, 

 "On the Breeding Habits of the Rainbow Darter (Ethcostoma 

 cceruleum)^ 



Miss Reeves, a graduate student of Professor Reighard in the 

 University of Michigan, has can-fully watched the breeding 

 habits of this dwarf perch, a species in which the males are 

 most brilliantly marked with blue and scarlet. 



It appears that the females do not select the brilliant males, 

 that the oldest and strongest males are most brilliant, that the 

 males know the females only by their color, that they mistake 

 young uncolored males for females, and that the bright-colored 

 males frighten away the younger ones by the display of their 

 gaudy fins and by blows of the tail or head. The brilliant 

 males were sucessful in pairing in 60 per cent, of the observed 

 cases. The sexes as usual in vertebrates are equal in number, and 

 the blue and scarlet colors belong to the males alone, these being 

 most brilliant at the beginning of the season — about April first. 



These observations give no support to the theory that the 

 females choose the gaudy males. It appears however that the 

 most brilliant males are the oldest and strongest, and that they 

 leave most descendants. This form of the theory of sexual selec- 

 tion would seem to be applicable to bright-colored fishes gen- 

 erally. 



Mr. E. W. Gudger 2 shows that the hammer-head shark 

 (Sphyma zygcena) feeds on sting-rays and that the mouth and 

 body of the shark are often full of broken-off stings. 50 of these 

 being extracted from a single shark 12J feet in length from 

 Beaufort harbor. 



Mr. Herbert W. Rand 3 discusses the functions of the spiracle 

 of the skate, one of these besides the usual function of respira- 

 tion is to keep the eyes clean by a jet of water. 



1 Biological Bulletin, XIV, 1907. 



' Science, XXV, p. 1005. 



■ Amer. Nat., XLI, p. 288. 



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