]4. RHYTIODUS. 305 



the root of the caudal, where it terminates in a black spot, which is 

 more distinct in young examples than in old ones. 



Erazil. 

 a-d. Fine specimens. Eiver Capin. Purchased of Mr. Stevens. 

 e. Half-grown. River Cupai. Purchased of Mr. Stevens. 



7. Anostomus isognathus. 



Schizodon isognathus, Kner, Denkschr. Acad. JFiss. IVien, 1859, xvii. 

 p. 163. taf. 0. fig. 13. 



D. 11-12. A. 10. L. lat. 44-46. L. transv. ^. 



The length of the head is a little more than one-fifth of the total 

 (without caudal) ; the lower jaw does not project beyond the upper. 

 Each jaw has the incisors crenulated, eight in number. A dark band 

 runs from the upper part of the gill-opening to the middle of the 

 fork of the caudal. {Kner.) 



Rio Cujaba. 



8. Anostomus nasutus. 



Schizodon nasutus, Kner, Denkschr. Acad. Wiss. Wicn, 1859, xvii. 

 p. 164. taf. 7. fig. 14. 



D. 11-12. A. 9-10. y. 10. L. lat. 42-44. L. transv. 5=5|. 



The length of the head is one-fifth of the total (without caudal). 

 Snout somewhat pointed, with the upper jaw projecting beyond the 

 lower. Each jaw with eight crenulated teeth. Coloration uniform : 

 a triangular spot on the root of the caudal fin, extending over the 

 middle of its fork. {Kner.) 



Irisanga. 



14. RHYTIODUS. 



Ehytiodus, Kner, Denkschr. Acad. Wiss. Wien, 1859, xni. p. 105. 



Doi-sal fin placed before the middle of the length of the body, 

 above the ventrals ; anal short. Body oblong, covered with scales 

 of moderate or rather small size. Belly rounded. Cleft of the mouth 

 very small ; intermaxillary and mandible with a single series of 

 small compressed teeth, longitudinally keeled in front : those in the 

 upper jaw with a single point, those in the lower with two keels and 

 two points ; palate toothless. Nostrils remote from each other. 

 Gill-openings rather narrow, the gill-membrane being grown to the 

 isthmus. Eyes with a broad adipose circular membrane. 



Brazil. 



I. Rhytiodus microlepis. 



Kner, I. c. taf. 7. fig. 15. 

 B.4. D. 11-12. A. 10. V. 9-10. L. lat. 87-90. L. transv. H::i-2. 



9-8 



The height of the body equals the length of the bead, and is con- 

 tained five times and one-third in the total (without caudal). Jaws 

 equal in length anteriorly. Coloration uniform bro^vn. {Kner.) 



Barra do Rio Negro. 



VOL. V. X 



