HYPOTHALMrrg. J89 



tliree inches in length. In the internal structure, 

 the only part noticed is the air-bladder, which is 

 large and is divided into two parts. 



B. 1I_D. 1/6— A. 3/10— C. 17— P. 1/10_V. 6— Vert. 42. 



HYPOTHALMUS, Spix. 



We have a single drawing of a fish referrible to 

 the genus Hypothalmus as characterized by Spix, 

 though it varies in many points from the restricted 

 characters laid down by Valenciennes, and in both 

 form, position of the fins, and internal structure, 

 would come in almost intermediately between the 

 genera Hypothalmus and Auchenipterus of the latter 

 author. In the structure of the branchial arches, 

 these fishes are remarkable in having interior pro- 

 cesses elongated and toothed or serrated, as in Core- 

 gonus ; and Agassiz has remarked that they may be 

 employed in capturing *' innumera animalcula te- 

 nella " * for their support. The notes of Mr. Schom- 

 burgk do not allude to this structure in our present 

 fish, which may either have been overlooked, or, 

 what is more probable, does not exist to the same 

 extent, as we learn that it took bait freely. The 

 internal structure, according to Agassiz, is nearly as 

 follows : — The intestines very small, with many 

 flexures; oesophagus short; stomach oblong, rounded 

 above; the abdominal cavity very squall, scarcely 

 equalling the head in length. Valenciennes restricts 

 * Spix. p. 16. 



