7. HEKOs, 299 



and on the opercles with a black dot. A round blackish blotch on 

 the root of the caudal fin. 

 Guatemala. 



a-b. Four inches long. River de Santa Isabel. From the Collection 

 of Messrs, Godman and Salvin. 



Description. — The length of the head is contained thrice and a 

 third in the total (without caudal). The eye is not very remote 

 from the profile of the nape, which is slightly curved. Head as high 

 as long; praeorbital scarcely wider than the orbit. Cleft of the 

 mouth rather narrow, horizontal, with the jaws equal anteriorly, and 

 with the maxillary not extending backwards to the vertical from the 

 front margin of the eye. The teeth in the outer series are the largest, 

 and provided Avith brown tips. Opercles scaly. 



Dorsal and anal fins not scaly ; doreal spines of moderate length 

 and strength, the length of the twelfth being one-third of that of the 

 head ; the soft dorsal and anal extend to the root of the caudal. The 

 free portion of the tail is as long as high. Caudal subtruncated, its 

 length being not quite one-fifth of the total. Pectoral shorter than 

 the head, but longer than the ventral, which does not extend to the 

 vent. 



25. Heros oblongus. 



Chi'omys oblonga, Casteln. Anim. nouv. ou raresAniei: Sud, Pom, p. 14. 



B.'i. A.f 



The height of the body is a little less than one- third of the total 

 length. (Cast.) 



Tocantins (Province of Goyaz). 



26. Heros autocMhon. 

 B. 5. D. i^. A. |. L. lat. 25. L, transv, 4/8. 



Scales on the cheek in two or three series. Body with dark cross- 

 bands. The width of the interorbital space is more than that of the 

 orbit. 



Brazil. 



a, b, c, d. Presented by Lord Stuart. 



Description. — The height of the body is one-half of the total length 

 (without caudal), the length of the head a little more than one-third. 

 The upper profile is strongly curved on the nape, concave before the 

 eyes, and straight on the snout. Head as high as long ; snout of 

 moderate extent, with the cleft of the mouth oblique and with the 

 jaws equal anteriorly. Jaws moderately protractile ; the maxillary 

 does not extend to the vertical from the anterior margin of the orbit. 

 Praeorbital square, rather narrower than the orbit. The width of 

 the interorbital space equals the extent of the snout, and is mere than 

 the diameter of the eye, which is one-fourth of the length of the 

 head. The eye is situated a little nearer to the extremity of the 



