194 SEXUAL DIMORPHISM 



partially removed during capture. In 1862 x Dr. Gunther 

 described a new species under the name A. lophotes, from three 

 preserved skins in Yarrell's collection. There was nothing 

 to indicate with certainty the locality from which these 

 specimens had been obtained, but in 1864 J. Couch stated 

 that he had examined a specimen of the same form obtained 

 at Plymouth, and in 1882 Professor Moseley captured a 

 specimen in the trawl off Lundy Island (Bristol Channel), 

 which he deposited in the British Museum. The chief 

 peculiarity of this supposed species was the considerable 

 elongation of the four or five anterior dorsal fin-rays. In 

 December 1889 I obtained from the trawlers at Plymouth a 

 considerable number of mature specimens both of A. lophotes 

 and A. laterna, and was struck with the great similarity of 

 the two forms in most of their characters. I soon found that 

 all typical specimens of the lophotes form were male, and all 

 specimens above a certain size of the laterna form were female, 

 while small specimens of both sexes were of the laterna form. 

 The development of the peculiarities of the mature male 

 takes place between the lengths 13'2 cm. and 14*7 cm., or 

 5*2 inches to 5*8 inches. 



The other differences between the lophotes form and the 

 laterna, on which Dr. Gunther relied, were the greater size of 

 the eye and the shorter maxillary bone in the former, and 

 these differences were found to exist in the specimens which 

 I compared. 



In the larger female specimens, more than 13*2 cm. in 

 length, an incipient development of the male peculiarities 

 exists, the second, third, fourth, and fifth dorsal rays being 

 slightly longer than the sixth. 



It must be noted that the reason for concluding that the 

 specimens with elongated rays are older and larger specimens 

 of the species A. laterna, is not that specimens without the 



1 Catalogue of Fishes, iv. p. 417. 



