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FISH. 121 



2. Mesites alpinus. Jen. 

 M. viridescenti-fuscus, dorso saturatiore ; hoc, et lateribus, et pinnis, nigro levissime 

 irroratis, immaculatis ; ventre niveo ; oculis majusculis. 



D. 10 ; A. 16 ; C. 16, &c. ; P. 13 ; V. 7. 

 Long. unc. 2. lin. 5. 



Form. — Very little difference in form between this and the last species. The eyes, however, are 

 decidedly larger, measuring in diameter one-third the length of the head. The head itself 

 also appears somewhat longer, being nearly one-fifth of the entire length. The anterior teeth 

 on the tongue do not seem much larger than the others. Fins similar. 



Colour. — {In spirits). Greenish brown, deepening in tint at the top of the back. Back, sides, 

 and fins, immaculate, but thickly powdered with minute dark specks, scarcely visible except 

 under a lens. These specks give the fins a more dusky appearance than they possess in the 

 last species. The belly appears to have been white. 



A second specimen does not differ from the above in any respect, except in being rather 

 smaller, and scarcely more than two inches in length. 



Habitat, Tierra del Fuego. 

 This species was taken by Mr. Darwin in alpine fresh-water lakes in Hardy 

 Peninsula, Tierra del Fuego. I have no hesitation in considering it distinct from 

 the last, as there are two specimens exactly similar, both shewing a larger eye, 

 and an entire absence of all approach to spots ; while the whole surface of the 

 back and sides is thickly irrorated with dark specks, a character which does not 

 appear in the plain varieties of the M. maculatus. 



3. Mesites attenuatus. Jen. 



Plate XXII. fig. 5. 

 M. viridescenti-fuscus, venire vix pallidiore ; dorso, et lateribus, pinnarumque radiis, 

 sparsim nigro levissimd irroratis, immaculatis : corpore prcegracili, antice attenuato ; 

 capite et oculis minor ibus. 



D. 11; A. 17; C. 16, &c. ; P. 12; V. 7. 

 Long. unc. 2. lin. 6. 



Forbi. — Rather more slender than either of the last two species, the body more attenuated ante- 

 riorly ; the head also smaller, though scarcely shorter. Mouth and eyes both smaller ; the 

 diameter of the latter not more than one-fourth of the length of the head. Teeth also rather 

 more minute as well as more numerous. The fins are similar, except that the ventrals appear 

 to stand rather more forward, being attached exactly in the middle of the entire length, ex- 

 cluding caudal : the distance from their insertion to the commencement of the anal is more 

 than twice their own length. The outer rays of the caudal are worn, but there was probably 

 a shallow notch when entire : the short accessory rays are very numerous, and form a very 

 distinct fringe along the upper and lower edges of the fleshy part of the tail. 



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