so, DOKAS. 201 



* Lateral shields more thau twenty. 



1. Doras costatus. 



Mystus, sp., Gronov. Mits. Ichth. ii. p. 24. pi. 5. figs. 1 & 2. 



Silurus costatus, L. St/st. Nut. i. p. 50(3. 



Cataphractus costatus, Bl. taf. 376. 



Doras costatus, Lacep. v. p. 117; Cuv. ^ Val. xv. p. 268. 



D. i^. A. 11. P. gig. V. 7. L. lat. 31-33. 



Lateral shields very high, covering the whole side of the body aud 

 tail, coarsely granular, not extending downwards to the base of the 

 anal fin. The humeral spine is about four times as long as high, 

 and reaches nearly to the posterior third of the pectoral spine ; the 

 posterior part of the tail shielded above and below. The maxillary 

 barbel reaches to the end of the humei-al spine. Dark brown ; a 

 yellow band along the lateral line, both bands convergent between 

 the eyes. Dorsal fin with a large blackish blotch. 



British Guiana ; Brazil. 



(/. Adult. Biitish Guiana. Presented by Sir R. Schomburgk. 

 b. Young. River Cupai. Purchased of Mr. Stevens. 



2. Doras armatulus. 



Doras armatulus, Cin: <5' Val. xv. p. 273 ; Kner, Sitzgsber. Wien. Acad. 

 185.5, xvii. p. 116. 



D. 1/6. A. 12. P. 1/6. V. 7. L. lat. 28-29. 



Lateral shields very high, covered with spines which are directed 

 backwards, the posterior projecting beyond the margin of each spine. 

 The humeral spine is twice as long as high ; the posterior part of the 

 tail shielded above and below. The maxillary barbels extend beyond 

 the base of the pectoral, the outer ones of the mandible being but 

 little, the two inner ones considerably shorter. Eye of moderate 

 size. Brown : a yellowish band commences above the eye, and runs 

 along the middle of the lateral shields to the end of the caudal fin ; 

 a less distinct band runs along the median line of the back. Doi-sal 

 fin with a large blackish blotch above. 



Brazil (Parana, Rio Guaporc and Rio Paraguay). 



• 3. Doras dentatus. 



Doras dentatus, Kner, Sitzgsber. Wien. Acad. 1855, xvii. p. 118. taf. 3. 

 fig. 3. 



D. 1/6. A. 12. P. 17. V. 7. L. lat. 31. 

 Lateral shields well developed, the height of the third being more 

 than one-half of the length of the head ; the following gradually 

 become lower, and the last caudal shields are scarcely one-third as 

 high as the third ; each shield with ridges radiating from the base 

 of the large central hook ; the ridges terminate in marginal hook- 

 lets, of which, however, there is only one above and below the cen- 

 tral hook of the middle and hinder shields. The humeral .spine 

 reaches to belnv the second lateral .shield, and is four times as long 



