O. ACARA. 279 



Description of the sjjecimen. — This species is very similar to A. 

 brasilieyisis in general form. The height of its body is contained 

 twice and a third in the total length (the caudal not included), the 

 length of the head three times. The nape of the neck is gently curved, 

 and its profile descends abruptly. The vridth of the interorbital 

 space equals that of the orbit, is two-sevenths of the length of the 

 head, and less than that of the snout. Snout compressed, moderately 

 elevated, the width of the pra^orbital being somewhat more than that 

 of the orbit. Cleft of the mouth slightly oblique, not extending to 

 the vertical from the orbit. The fold of the lower lip is interrupted 

 in the middle. The lower limb of the prajoperculum is only half as 

 long as the posterior. More than one-half of the operculum is naked, 

 only its upper portion and basal margin being covered with scales 

 larger than those on the cheek. There are twelve series of scales 

 between the throat and the root of the ventral. 



Dorsal spines of moderate strength, gradually increasing in length 

 posteriorly ; the length of the ninth is somewhat more than one-half 

 of that of the head. The middle of the soft dorsal and anal produced, 

 and extending beyond the- middle of the caudal, which is subtrun- 

 cated. Pectoral rather shorter than the head, extending to the origin 

 of the anal ; ventral with a filament. 



Brownish-olive, with a black blotch below the ninth and tenth 

 scales of the lateral line ; the scales between the origin of the lateral 

 line and the ventrals dark, with steel-blue dots ; an indistinct dark 

 band rises from the eye to the nape ; the posterior parts of the dorsal 

 and anal, and the caudal with round whitish spots. 



It is possible that this species is identical with Acai'a hecJcelii 

 (Mull. & Trosch. in Schomb. Guiana, iii. p. 624), which is described 

 as follows : — 



The lower (?) orbital bone is longer than the diameter of the eye ; 

 five series of scales on the check ; the nostril is situated at one-third 

 of the distance of the eye from the snout. A black spot on the side, 

 below the lateral line ; tail -without spot ; tins dotted with white. 



5. Acara vittata. 

 Heckel, Bras. FIuss-Fische, p. 346. 



D. }3. A. |. L. lat. 24. L. transv. 2/8. 



Three series of scales on the cheek ; pra^orbital as Avide as the orbit 

 (in specimens from 3 to 5 inches long) ; the greatest breadth of the 

 head is three-fifths of its length. Cleft of the mouth rather oblique. 

 A black spot on the middle of the sides, another on the upper part 

 of the root of the caudal ; sometimes a blackish band from the gill- 

 opening to the lateral spot ; another from the nape of the neck to 

 the orbit, narrower below the eye, and continued to the lower prit- 

 opercular margin, k light streak from the eye to the nostril. 



Province of Matagrosso. 



a. Adult. Purchased of Mr. Scrivener. 



