546 



PROF, W. B. BENHAM AND MR. W. J. DUNBAR ON [May 15, 



being due to minute pigment-cells below the silver " (Benham, loc, 

 cit.). After being in formol for a couple of years these marks are 

 still present, and more distinct than in the recently dead fish. 

 Another feature in which B. parkeri differs from the specimens of 

 7?. glesne is in proportions of parts and in the greater number of 

 dorsal fin-rays : for whereas, in most of specimens of the full-grown 

 fish, these number from 200-260, as given for difierent individuals, 

 there are 400-500 in the specimens of R.2xirkeri ; but Forbes gives 

 422 as the total number in the full-grown individual described 

 by him. 



As the number of fin-rays in the dorsal fin has been utilised by 

 ichthyologists as a specific character, this variation in the adults 

 -of what are regarded as one species is interesting. 



For convenience of a comparison of " ^. ^jfwA'eH " with the 

 adult forms, I here tabulate the sei'ies of measurements adopted 

 by Parker and followed by Forbes and Clarke : — 



The specimen A is the one described in the body of my article ; 

 B is that referred to in the footnote (1. p. 200), the skull of which 

 is described below. 



In the adult fish the proportion 



height 



length 

 head-length 

 total length 

 preanal length 

 total length 

 head-length 



varies from 



preanal length " 

 height 

 " " " preanal length " 



It is remarkable that, in the case of the first three relations, the 

 high numbers are found in the longest specimen, that described 

 by Forbes, in which, too, the number of fin-rays is excessive. 



