202 SILTTKID.E. 



as high ; it terminates in a point, and its upper and lower margins 

 are prominent, ridge-like, and denticulated. The posterior part of 

 the tail is shielded above and below. The maxillary barbel does not 

 reach to the end of the humeral spine ; none of the barbels are 

 fringed. Brown, without yellow lateral band; a blackish-brown 

 spot behind each hook of the lateral shields. {Kner.') 

 Surinam. 



4. Doras hancockii. 



Doras costata, Hancock, Zool. Journ. iv. p. 242 (not L.). 

 hancockii, Cuv. 8f Val. xv. p. 279. 



D. 1/6. A. 9. P. 1/6. V. 7. L. lat. 29-33. 



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

 tail, extending downwards to the root of the anal, with numerous 

 longitudinal ridges, each of which terminates in a small marginal 

 point. The humeral process is rather broader than the pectoral 

 spine, and does not quite extend to its posterior third. Hinder part 

 of the tail shielded above and below. Adipose fin without spinous 

 ray. The maxillary barbel reaches to the root of the pectoral. 

 Brown, a lighter band along the lateral line. 



Demerara ; Brazil. 



a. Type of the species : stuffed. Presented by Dr. Hancock. 



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



5. Doras muricus. 

 ? Marcgrav. p. 174. 



? Doras granulosus, Valmc. in Humb. Observ. Zool. ii. p. 184. 

 ? Doras maculatus, Valenc. in cFOrb. Voy. Anier. Merid. Poiss. pi. 5. 



fig. 3 ; Cuv. # Val. xv. p. 281. 

 Doras muricus, Kner, Sitzgsber. Wien. Acad. 1855, xvii. p. 129. 



D. 1/6. A. 13. P. 1/9. V. 7. L. lat. 27. 



Lateral shields rather small, lower than the hinder portion of the 

 tail. Humeral process granulated, slender, much narrower than, 

 and extending to the hinder fourth of, the pectoral spine. Dorsal 

 spine serrated in front and behind. The upper and lower surfaces 

 of the tail are not shielded ; adipose fin small, without spinous ray. 

 Fins with brown dots ; skin on the back with minute' black tubercles. 



Brazil ; Buenos Ayres. 

 a. Adult, 21 inches long : stuffed. Demerara ? 



6. Doras afiinis. 

 Doras affinis, Kner, Sitzgsber. Wien. Acad. 1855, xvii. p. 121. fig. 1. 

 D. 1/6. A. 12. P. 1/5. V. 7. L. lat. 25-26. 

 Lateral shields very high, nearly entirely covered with skin, each 

 with a series of small marginal spines. The humeral process is long, 

 not broader than, and extending to the posterior third of, the pec- 

 toral spine. Tail without shields on its upper and lower surfaces. 

 Caudal fin subtruncated. Dorsal spine without any serrature. Bar- 



