BUTTEKFLY BLENNY. 213 



specimen of this fish was taken by a trawl-net in 1845, 

 but the spot on the first dorsal fin was so obscure as 

 scarcely to be noticed." 



It is therefore with the more satisfaction that I can 

 record the possession of two specimens, one taken in 

 Weymouth Bay from deep water, the other among the 

 hanging weeds of this shore. Both were in full develop- 

 ment and high colour, the spot on the fin from which 

 both the specific and the popular names are derived, 

 strongly marked, so that I am enabled to give a repre- 

 sentation of this interesting fish in its vivid hues, as it 

 appears in life and health. 



The form is thick-set, as is that of the other more 

 common species of the genus ; the forehead is, however, 

 rounded and less abrupt, which imparts to it a different 

 physiognomy. The fins are ample, with the exception 

 of the ventrals, which in all this genus consist of two 

 rays each ; the pectorals Very large, nearly circular, 

 transparent and colourless, with pearly rays. The dorsal 

 is divided into two portions, of which the first is ele- 

 vated like a tall sail, the first ray standing up a long 

 way beyond the membrane. Its colour is smoke-brown, 

 deeper at the summit ; towards the hind end of this 

 portion there is a large round black spot, surrounded 

 by a well-defined pale ring; very conspicuous, indeed, 

 in my specimens, and strikingly suggestive of the eye- 



