FISH. 75 



not feel authorised in describing it as distinct without seeing more specimens. 

 It is stated by the authors above mentioned, that the fin-ray formula of the 

 S. maculatus is the same as that of the S. Fiatola: in the specimen here described, 

 the number of rays in the dorsal and anal fins appear to me somewhat greater ; 

 but as the spines of these fins are very minute at their commencement, and not 

 readily counted, nor very distinguishable from the soft rays, perhaps the discre- 

 pancy may arise from a difference in the mode of computation. What is more to 

 be noted is, that the spots, although they agree in form and mode of arrangement, 

 are said by Mr. Darwin, in his notes taken from the recent fish, to have been 

 "leaden;" whereas it is stated in the " Histoire des Poissons" that they are 

 " yellow." Perhaps they may vary in colour according to the period of the year. 

 There is likewise a difference in locality as regards latitude. The S. maculatus 

 is said to be common in the market at Lima, and to have been brought also, both 

 by M. D'Orbigny and M. Gay, from Valparaiso. Mr. Darwin's specimen, 

 however, was taken as far south on the western coast of S. America as Chiloe. 



Mr. Darwin's collection contains another specimen, either of the same species 

 as that described above, or one so extremely similar to it as not to be distinguish- 

 able in the case of this specimen, which is in too bad preservation to admit of an 

 accurate description of it being given. The following, however, are Mr. Darwin's 

 notes taken from the recent fish : — 

 Colour. — " Whole body silvery ; upper part of the back iridescent blue, lower greenish ; spotted 



with coppery-lead circular patches." — D. 



This specimen measures ten inches and a half in length. It will be observed 

 that the colour of the spots is still said to have been " lead," though inclining to 

 coppery. It was not taken at the same place as the other, but at Port St. Julian, 

 in central Patagonia; if therefore they are both referable to the S. maculatus, this 

 species will have been proved to have a wide range in point of latitude, and also 

 to occur on both sides of the S. American Continent, which is remarkable, con- 

 sidering that it is found so high up the western side as Lima. 



Family.— TEUTHYDID^. 



1. ACANTHURUS TRIOSTEGUS. SI. Scllfl. 



Acanthurus triostegus, Cuv. et Vol. Hist, des Poiss. torn. x. p. 144. 

 Hirudo, Benn. Fish of Ceyl. pi. xi. 



This species, which appears to be well known, and to have been described by 

 several authors, was found by Mr. Darwin on coral reefs at the Keeling Islands. 

 Cuvier and Valenciennes observe that it has a wide range through the Indian and 



