192 HYPOTHA.LMUS. 



eyes oval, situate in the middle of the head; the 

 iris yellow. Tongue round and fleshy ; jaws nearly 

 equal ; teeth, a series thickly set in each jaw, with 

 two like processes on the palate. Intestines form 

 only one flexure, and the vent is situate equidistant 

 from the ventral and anal fins ; milt long and double. 

 The dawalla lives an hour after being taken out of 

 the water, and reaches a length sometimes of two 

 feet and a half. In the creeks, near the thickly 

 populated districts, they are very hard to take, and 

 will only bite at live bait; but in ascending the 

 Essequibo, where it has fewer inhabitants, we found 

 no difficulty in taking them with hooks baited in 

 the usual way ; we also obtained a good number at 

 Fort St. Joaquim, in the Rio Branco." 



D. 7— V. 7— A. 38— C. 35— Br. 11— Ribs, 11 pairs— Vert. 52. 



There will thus, from the foregoing description, 

 be seen to be a considerable discrepancy in the 

 structure as given in Mr. Schomburgk's notes and 

 the observations of Agassiz and Yalenciennes ; and 

 we would desire that particular attention should be 

 given to the general anatomy and to that of the 

 branchial arches. We have no details either of the 

 habits of these fishes, or of the place and manner of 

 their spawning. 



The only other drawing in the Collection, be- 

 longing to the Siluridae, which we can notice, is an 

 imperfect sketch of the large fish, Lau-lau^ alluded 

 to in the Introduction (p. 99). It is so imperfectly 

 finished, that it is not possible to make out the spe- 



