530 Mr. C. T. Rei?an on tlie 



o' 



its stay in the preservative, the more like an adipose fin the 

 fold may become.'^ 



Suffieient has been said to show that Messrs. Evermann 

 and Kendall regard the structnre of tiie adipose fiti as of 

 little value for the distinction of species. Tliey state that 

 their specimens undoubtedly Ijclong to one species and yet 

 that individuals fall respectively into several of my main 

 divisions (based on the structure of the adipose fin), the only 

 condition unrepresented being that of a well-developed adi- 

 pose fin without trace of a spine, which they would hardly 

 expect to find in specimens which have been only so recently 

 submitted to the action of alcohol. 



The position of the ventral fins is a character to which I 

 have attached considerable importance for the distinction of 

 species, but the authors quoted above state that in the males 

 the veiitrals are inserted farther forward than in the females, 

 and they give figures of a male fish in which the insertion 

 of the ventrals is below the origin of the dorsal, and of a 

 female with the ventrals inserted below the middle of the 

 dorsal. They continue : '' In the males, as already remarked, 

 the ventrals are inserted farther forward than in the females ; 

 therefore, comparison of extent of pectorals with ventrals or 

 ventrals with proximity to vent is of no value. In fact, 

 there is such a range of variation in these characters, 

 regarded by Regan as showing specific differences, that there 

 arises a serious distrust of the value of any of them for that 

 purpose.''^ 



They conclude that the number of species should be con- 

 siderably reduced, suggesting that the five alleged Peruvian 

 species may be one, or at the most two. They consider 

 A. prenadilla and A. Eiyenmanui to be synonyms of 

 A. cyclopum, suggest that A. Iiomodon may be the male of 

 A. Ouentheri, and think that the characters given for the 

 distinction of ^. IVhymperi, A.fissidens, A. sabalo, A. Taczan- 

 owskii, and A. VaiUanti are scarcely suflficient. 



On receiving Messrs. Evermann and Kendall's surprising 

 paper I at once proceeded to re-examine all the specimens of 

 Aryes * in the British Museum Collection, with the result 

 that I must entirely adhere to my original arrangement, 

 Messrs. Evermann and Kendall's views being evidently the 

 result of a hasty study of insufficient material. 



I maintain my grouping of the species according to the 

 structure of the adipose fin. The first division, to which 

 the Pimelodus cyclopwu of Humboldt most certainly 



* 85 specimens, representing 1(5 or 17 species, from Peru, Ecuador, 

 Colombia, and Venezuela. 



