NATURAL SCIENCES OF PHILADELPHIA. 91 



Lacepede describes the color of his species thus : 



" II a en effet la nageoires de la queue ainsi que les autres nageoires, jaunes 

 ou jaunatres ; elles sout d'ailleures pointillees de noir. Une couleur brune 

 argentine regne sur la partie superieure de l'animal, et un blanc argente sur 

 l'inferieure. L 'iris est jaune." 



This description, it must be confessed, is more applicable to the so-called 

 Homoprion xanthurus than to the Leiostomus obliquics, especially that part which 

 refers to the silvery whiteness of the lower parts. But it also equally applies 

 to an individual of the latter species, whose bands and humeral spot have 

 faded, and whose seales have been rubbed from the belly, as is frequently the 

 case with old, dried or alcoholic specimens. 



Bosc, while taking his description and figure of the species from a dried or 

 preserved specimen of the Leiostomus obliquus, from which the bands and hu- 

 meral spot had disappeared, to complete the description of the color, may pos- 

 sibly have had either recourse to a fresh specimen of the "yellow tail," or 

 Homoprion xanthurus, which was casually and separately examined, or per- 

 haps relied partly on the description of another. At most, the description of 

 the coloration is the only documentary evidence to which we can appeal in sup- 

 port of the views of the identity of the Homoprion xanthurus with Leistomus 

 xanthurus. Appeal must be then made to other sources. 



As already mentioned, Cuvier and Valenciennes have informed us that 

 Bosc had sent to them the same species as that described by Lacepede.* 

 This statement may be thus explained. 



The specimen whose anatomical characters were described and figured by 

 Bosc, could not have been the one sent ; that forwarded was believed to be- 

 long to the same species as the one described, on account of the identity of 

 popular names. The original, with the color faded, had probably been 

 pronounced to be the "yellow tail." The statement was doubtless 

 accepted as true, and no comparison made to ascertain whether such was 

 the case. A demand having been afterwards made for a specimen of the 

 species described, one of the true " Yellow tail " was obtained and sent as 

 belonging to it, reliance being placed on the correct application of the popular 

 names. This theory is assumed, as it is deemed to be inadmissible to go be- 

 hind the description to such a position, when the description and specimen so 

 strongly conflict, and when that description is so applicable to a common 

 species found in the same regions. It is not stated that the type of Bosc's 

 original description and figure was sent. The name of Leiostomus is therefore 

 retained for the species without teeth on the lower jaw, and with an entire 

 preoperculum. 



While it may be admitted that the name of Leiostomus can be retained for 

 the genus, it may be still questioned whether the specific name can be ac- 

 cepted. 



As the description, so far as it goes, is applicable to the Leiostomus obliquus, 

 and the fault is simply due to an omission of mention of the oblique bands 

 and the humeral spot, which are frequently faded, we are of the opinion that 

 the specific name must be also retained. 



Cuvier and Valenciennes' assignation of teeth to both jaws of the Leiostomus 

 lonneralis can be only explained on the supposition of their belief in the uni- 

 versality of the characters of dentition, and their conclusion that the species 

 must have teeth because apparently nearly allied ones had. 



The rest of the description and the radial formula are more applicable to 

 that species which has been called by the same name by subsequent natural- 

 ists, or the Homoprion xanthurus of Holbrook. 



Can the specific name of xanthurus be retained for the species described under 

 that name ? 



*"M. Bosc, qui avaitfoumi a JM. de Lacepede le dessin et la note dont il a tire son ar" 

 ticle, a bien vouki nous donner le poisson uimeme, et nous sommes ainsi assures de l'es 

 pece." 



1861.] 



