27. HYPOPHTHALMUS. '67 



The teeth on the palate form two separate patches, occupying the 

 front of the vomer. The barbels are thin, and of nearly equal 

 length, extending to, or neai'ly to, the middle of the pectoral fin : 

 one is above and a little in front of the angle of the mouth ; the 

 mandibulaiy barbels are placed one close behind the other, nearly in 

 the vertical from the maxQlary barbel. The eye is above the angle 

 of the mouth ; there is a groove below the eye. 



The dorsal fin is a little behind the middle of the distance between 

 the nape of the neck and the root of the caudal fin ; its height is 

 somewhat less than the length of the head. Adipose fin very small, 

 lobuliform. Caudal forked, with the lobes equal in length and 

 pointed ; their length is about one-fifth of the total. The anal is 

 very long, -vnth fleshy base, extending to the root of the caudal ; its 

 distance from the gill-opening is more than the length of the head. 

 Pectoral as long as the head, extending beyond the base of the ven- 

 tral fin ; the latter reaches slightly beyond the origin of the anal. 



Blackish brown, finely marbled with black. 



Essequibo. 



a-b. Three and a half inches long. Purchased of Mr. Ehrhardt. 



27. HYPOPHTHALMUS. 



H\'pophthalnuis, .sp., Sj»'j-. 

 Hypophthalmus, Ctir. ^- Val. xv. p. 224. 



ri\'poplithalnuis aud Pseudohypophthalmus, Block. Nederl. Tychchr. 

 'Dicrk. 1863, p. 109. 



Adipose fin very small ; dorsal fin short, with seven rays, the first 

 of which is slightly spinous ; anal very long. The lower jaw is 

 rather the longer. Barbels six, those of the mandible long. Teeth 

 neither in the jaws nor on the vomer ; intermaxillaries very feeble. 

 Head covered ^vith skin. Eye of moderate size, situated behind and 

 below the angle of the mouth. GiU-openings exceedingly wide, ex- 

 tending nearly to the symphysis of the mandibles. Air-bladder 

 none. Ventrals .small, six-rayed, inserted before the dorsal. 



South America. 



The gill-opening is exceedingly \vide, the gill-membranes being 

 scarcely united in front. The gill-rakers are fine, very long, closely 

 set ; the first branchial arch has only one row of gUl-rakers along 

 its outer margin, the inner margin being lined with a broad mem- 

 brane ; the second, third, and fourth arches have two rows of gill- 

 rakers, the fourth being destitute of lamcllnc, and entirely attached to 

 the thorax, without lea%'ing an open .slit behind. 



I. Hypophthalmus edentatus. 



Hj-pophthalmu.^* edentatus, Spix, I'l'sc. Bnts. p. 10. tab. 9. 

 — '- — spixii. Cm: (^ I'al. xv. p. 2.J1 ; Kiwr, Sitzysher. Wien. Acad. xxvi. 

 1858, p. 446. 



D. 1/6. A. 72. P. 1/17. V. 7. 



The length of the head is rather less than ono-fourth of the total 



p2 



