354 chahactnid-e. 



rounded. Cleft of the mouth wide ; teeth conical, in a single series, 

 smaller ones being intermixed with strong canine teeth ; palatine 

 with a series of small teeth. Nostrils close together, separated by a 

 membrane only. Gill-openings wide, the gill-membranes being free 

 and separate; gill-rakers very short. Intestinal tract with a single 

 circumvolution ; caecal sac of stomach very long. 

 South America, east of the Andes. 



The species may be referred to two groups : — 

 a. Maxillary with canine teeth, p. 354. 

 /3. All the maxillary teeth of equal length, p. 355. 



a. Maxillary with canine teeth. 



1. Xiphotfhainphus falcirostris. 



Hydrocyon falcirostris, Cuv. M6m. Mm. v. p. 361. pi. 27. fig. 3. 

 Xiphorhamphiis falcirostris, Mull. 8f Trosch. Hor. Ichth. i. p. 18 ; Kner, 

 Denksehr. Acad. Wiss. Wien, 1860, xviii. p. 58. 



D. 11. A. 22-25. V. 3. L. lat. 160. 



The height of the body is two-elevenths, one-sixth or one-seventh 

 of the total length (without caudal), the length of the head two- 

 sevenths. Snout much elongate, its length being equal to the dis- 

 tance between the anterior margin of the orbit and the posterior 

 of the praeoperculum ; the entire dorsal fin is in the hinder third of 

 the total length (without caudal). A round deep-black spot on the 

 root of the caudal fin, none on the shoulder. 



Brazil, Guianas. 

 a. Adult : stuffed. Demerara. From the Collection of the Zoolo- 

 gical Society, 

 o. Half-grown. Kiver Cupai. Purchased of Mr. Stevens. 



It is very improbable that the description given by Valenciennes 

 in the 22nd volume, p. 341, is taken from the typical specimen as 

 he asserts. Cuvier says distinctly that his specimen was 20 inches 

 long, that it had more than 100 scales in a longitudinal line, and 25 

 anal rays. Valenciennes, however, describes his specimen as being 

 17 inches long, and as having 200 scales in a longitudinal line, and 

 30 anal rays. 



2. Xiphorhaniphus falcatus. 



Salmo falcatus, Bloch, taf. 385. 



Xiphorhamphus falcatus, Mull, fy Trosch. Hor. Ichth. i. p. 17; Kner, 



i>e?ikschr. Acad. Wiss. Wien, 1860, xviii. p. 57. 

 Xiphorhynchus falcatus, Cuv. 8f Vol. xxii. p. 337. 



B. 4. D. 11. A. 28-30. V. 8. L. lat. 100-120* 



The height of the body is one-fifth or two-elevenths of the total 



* M tiller and Troschel say that the lateral line is composed of " about " 80 scales, 

 whilst a higher number has been found by Valenciennes and Kner. 



