Dr. A. Giinther on the History of Echeneis. 397 



varies between twenty-one and twenty-three, proves that in fact 

 he has confounded E. naucrates and E. lineata, Holbr. He in- 

 forms his readers that all the species are natives of the tropical 

 seas, and that they are to be considered only as accidental visi- 

 tors to the coast of New York ; and, a few lines further on, states 

 that the species is not uncommon on the coast of Long Island. 

 He mentions an instance of a specimen having ascended a con- 

 siderable distance up the Hudson River. Those species which 

 have been established on differences in the number of caudal 

 and dorsal rays, or differences in the form of the caudal fin from 

 that observed by Linnaeus and subsequent ichthyologists in E. 

 naucrates, appear to rest on a far more solid foundation. The 

 variations, indeed, are great ; and only an examination of a great 

 number of specimens of different ages can lead us to a correct 

 opinion on the subject. 



1. We find, then, that the number of laminae varies between 

 twenty-two and twenty-five. Specimens with twenty-one or 

 twenty-six laminae are of rare occurrence. The number of dorsal 

 rays varies between thirty-three and forty-one ; that of the anal 

 rays between thirty-two and thirty-eight. All the specimens in 

 which these variations have been ascertained are otherwise exactly 

 similar to one another, and especially show the same relative 

 proportions of the different parts. 



2. The caudal fin undergoes extraordinary alterations with 

 age. In young specimens about 4 inches in length, the middle 

 portion of the fin is produced into a long filiform lobe. This lobe 

 gradually becomes shorter, and the fin shows a rounded margin 

 in fishes of middle age, with the middle portion sometimes di- 

 stinctly projecting beyond the level of the margin. When, 

 finally, the fish approaches the mature state, the upper and 

 lower lobes are produced, and the fin becomes subcrescentic or 

 really forked. Even in this state, I have observed specimens in 

 which the middle part of the fin is slightly produced, so that it 

 has the appearance of having three lobes. Riippell * has also 

 observed slighter changes in the form of the caudal. 



The following species have been founded on such variations : 

 Echeneis lunata by Bancroft f, Echeneis vittata by Lowe J, a 

 second Echeneis vittata by Riippell , and finally, Echeneis aus- 

 tralisty Griffith || . 



The authors who remain to be mentioned have not contributed 



* Neue Wirbelth. Fische, p. 82. 



t Proceed. Comm. Zool. Soc. i. p. 134, and Zool. Journ. v. p. 411, pi. 18 

 (indifferent description and figure). 



t Proc. Zool. Soc. 1839, p. 89 ; and Fishes of Madeira, p. 77. tab. 11. 



N. W. Fische, p. 82. 



|| Anim, Kingd. Pise. pi. opp. p.504 ; Bennett, Whaling Voyage, ii. p, 273. 



