80. doras. 203 



bels simple, those of the maxillary extending to the extremity of the 

 humeral process. Eye of moderate size, the superciliary margin not 

 elevated. Brownish, body and fins with darker spots ; a light band 

 along the middle of the sides ; caudal fin dark, with a broad light 

 cross-band. (Kner.) 



Rio Branco and Guapore. 



Amblydoras truncatus, Bleek. (Nederl. Tydschr. Dierk. 1863, i. 

 p. 18), has been separated from the preceding species, but its cha- 

 racters have not been sufficiently indicated. 



7. Doras weddellii. 

 ? Doras weddellii, Caste///. A/ii/n. Amer. Sud, Poiss. p. 48. pi. 17. fig. 1. 

 D. l/4(?). A. 11. V. 7. L. lat. 27. 

 Lateral shields low, not quite half as high as the hind portion of 

 the tail ; there is a small spine above and below the large one. The 

 free portion of the tail has a series of small scutes above and below. 

 Head broader than high ; its length to the basal bone of the dorsal 

 spine is two-fifths of the total (without caudal), its length to the 

 gill-opening two-sevenths. • The height of the body is contained 

 thrice and two-thirds in the total length (without caudal). Snout 

 obtusely rounded ; the maxillary barbels extend beyond the end of 

 the head. Nape broadly shielded, the least width of the nuchal 

 carapace being equal to that of the interorbital space. The humeral 

 process is narrow, pointed behind, extending to the hinder fourth of 

 the pectoral snine ; it is provided with a series of small tubercles. 

 Dorsal spine strong, without any serrature, four-fifths of the length 

 of the head. The pectoral spine is still stronger and longer, strongly 

 serrated along both edges. Caudal fin forked. Superciliary edge 

 '.lot elevated. Brown above, marbled with darker ; an irregular 

 series of small black spots above and below the lateral line. 



Brazil. 

 a. Four and a half inches long. Santarem. From Mr. Bates's Col- 

 lection. 



8. Doras asterifrons. 



Doras asterifrons (HecJcel), Kner, Sitziinqsber. Wien. Acad. 1855, xvii. 

 p. 123. fig. 2. 



D. 1/6. A. 11-12. P. ^. V. 7. L. lat. 24-25. 



Lateral shields high, but partly covered with skin ; each is pro- 

 vided with a triangular prominent spine above and below the central 

 hook ; several other small spines occupy the posterior margins. The 

 humeral process is long, not broader than, and extending to beyond 

 the middle of, the pectoral spine ; it is tapering and provided with a 

 series of small curved spines. The pectoral spine extends backwards 

 to beyond the root of the ventral ; a portion of the bones of the thorax 

 are free, not covered with skin, striated. Dorsal spine finely ser- 

 rated in front, without denticulations behind ; there is only one very 

 small shield on the upper and lower surfaces of the tail, immediately 



