NATURAL SCIENCES OF PHILADELPHIA. 61 



As Mitchill's notice of Echeneis albicauda gives a relative width, to the 

 body even greater than that attributed by Giinther to his E. Holhrookii, and 

 far greater than that assigned by him to E. naucrat.es, and as Echeneis albi- 

 cauda has "twenty-one bars across the shield," also in E. Holhrookii 

 "the number of laminas has been constantly found to be twenty-one a 

 number of very rare occurrence in E. naucrates," the reasons for Giinther's 

 insistence on the reference of Mitchill's name to E. naucrates and bestowal 

 of a new one on his species are not evident. I cannot appreciate the force of 

 his remark that Mitchill's " is an imaginary species," and that the name, 

 " as is qui'e clear, was originally not intended for the fish afterwards de- 

 scribed by Holbrook as E. lineata, but merely for specimens of E. naucrates 

 with a white margin to the fins." 



Long before the communications of Mitchill, and as early as the year 1788, 

 a species of the genus Leptechcneis was made known by Zuiew in a special 

 article (Eche?ieidis nova species) in the Nova Acta Academise Scientiarum Im- 

 perialis Petropolitanae (iv. 279 283, tab. VI.) The species was well and 

 elaborately described and illustrated, and was especially distinguished from 

 E. naucrates by the much longer lower jaw and the longer disk, which 

 nevertheless had a smaller number of lamina? (20.) The species thus intro- 

 duced was named Echeneis neucratoides ; its habitat was unknown. 



While it is thus seen that two forms with a comparatively small number 

 of lamina? had been early made known, and that the proportions assigned to 

 one agreed nearly with those attributed to E. Holhrookii by Giinther, it is 

 necessary to add that none of the specimens examined by myself had so long 

 a disk or so wide a body as the individuals noticed by Giinther, although I 

 have had tbe opportunity of examining specimens of the genus exhibiting 

 every gradation between eighteen and twenty-five lamina?. I shall not, how- 

 ever, offer any decided opinion at present, but close with the assertion that 

 DeKay's and Holbrook's specimens had not the proportions of the E. Hol- 

 hrookii of the Acanthopterygian Fishes, but agreed with those seen by my- 

 self. As GQnther's E. Holhrookii was entirely founded on the E. lineata of 

 Holbrook in the first instance, that name must of course be considered as a 

 synonym. 



The Echeneis scutata of Giinther had first received a name from F. D. Ben- 

 nett in his ' ' Narrative of a Whaling Voyage round the Globe, from the year 

 1833 to 1836."* In that work, Bennett gave a very recognizable description 

 of it under the name Echeneis austrahs.\ Bennett's name has been referred 

 by Giinther to the synonymy of Lrptecheneis neucrates, like E. albicauda, 

 but, as will be shown, erroneously. Bennett has stated that the E. australis 

 exceeds the E. remora especially recognized by Giinther as that species in 

 size. "One individual captured, and which was by no means the largest 

 one observed, measured one foot five inches in length, and was proportionally 

 broad." This statement at once would render the identity of the species 

 with E. nait'crates extremely improbable, as the latter species has an incom- 

 parably more slender body. The further statement that the dorsal has " 21" 

 rays, and the anal "24," completes the evidence of its difference from L. 

 neucrates, that species having the formula D. "(21) 22 25 (2(3) 3341. A 

 3238," (Giinther). As Bennett's formula (" D. 21. A. 24") specially 

 agrees with Giinther's formula of E. scutata (" D. 27 | 22. A. 2123"), 

 and, as of three examples of Bennett's species, "one only had 24 stride on 

 the buckler, the other two had 26," thus also specifically agreeing with E. scu- 

 tata (" D. 27 | "), the identity of the two nominal species is almost certain, 

 and Bennett's name (Remilegia australis,) as the prior one, must be accepted. 



* Op.cit., vol. ii. 1840, p. 273. 



t The name of Echeneis australis was first introduced into Science by Bennett, as that of anew 

 ppecies. A Lepteclieneis probably L. neucrates had beca previously figured in Griffith's Cuvier 

 under the English name ot " Australian remora," but no attempt at identification of the two was 

 made by Bennett, and the species belong to widely distinct genera. 



1864.] 



