FISH. 6l 



extend as far eastward as the Keeling Islands, where Mr. Darwin's specimen was 

 obtained. 



The Spams enjthrurus of Bloch (pi. 261) is so extremely unlike the present 

 species both in form and colours, that, except on the authority of MM. Cuvier 

 and Valenciennes, who state that they had seen Bloch's original specimen, no one 

 could have suspected that the figure had been intended for it. 



Family— CILETODONTIM. 



Ch^itodon setifer. Bloch. 



Chffitodon setifer, Bloch, Ichth. pi. 425. fig. 1. 

 Cm. et Val. Hist, des Poiss. torn. vii. p. 58. 



F RM.-This species is one of those characterized by a prolongation of a portion of the soft 

 dorsal fin. In the present specimen it is the sixth soft ray which is thus prolonged. The total 

 length of this ray, measured from the root, is half the entire length of the fish; and that 

 portion of it which exceeds the adjoining rays is rather more than half. Although the 

 pieopeicle can hardly be called denticulated, yet there are some faint traces of rudimentary 

 denticulations at the lower angle. The general form, in all other respects, agrees with the 

 descriptions of Cuvier and other authors. 



D. 13/24 ; A. 3/21 ; C. 17, and 6 short; P. 16, the first short ; V. 1/5. 

 Length 6 inc. 3 lines. 



Colour.—" Body pale, with narrow dark straight lines which form network : across the eye a 

 black band : posterior half of the body bright orange : upper part of the prolongation of the 

 dorsal fin edged with black, and a round patch of the same."— D. The black ocellus extends 

 from the fifth to the thirteenth ray of the soft dorsal. There is no trace of the four red or 

 yellow streaks said by Cuvier and Valenciennes to cross the forehead from eye to eye; but 

 probably they are effaced by the action of the spirit. 



A second specimen only differs from the above in being smaller, measuring in length not quite five 

 inches ; in having the fifth (instead of sixth) ray in the soft dorsal prolonged ; and in the 

 ocellus extending from the fifth to the tenth ray only. In the last two respects it agrees better 

 with the description in the < Histoire des Poissons.' The filamentous ray terminates in an 

 extremely fine hair, which leads me to think that the extreme portion of this ray in the first 

 specimen has been broken off. 



Habitat, Keeling Island, Indian Ocean. 



