22 ON THE SPECIES OF THE GENUS ANOSTOMUS. 



Lake Hyanuary, Lake Saraca, Manacapouru, Manaos, 

 Obydos, Rio Puty, San Paolo, Serpa, Tabatinga, Teffe, 

 Tonantins, Villa Bella. 



ANOSTOMUS DISSIMILIS, sp. n. 

 D. 12; A. 11; V. 9 ; L.I. 43-45 ; L. tr._L. 



4(5) 



Nearly related to both of the preceding. Darker in 

 color than A. fasciatus, and distinguished from it, as from 

 A. viltatus, by the absence of a spot on the base of the 

 tail. The blotches on the flanks vary greatly, being re- 

 duced, irregular, faint, or entirely absent. Length of 

 head equal to the depth of body and contained in total 

 length, without caudal, four and two-thirds times. The 

 mouth opens forward, the lower jaw is very little the 

 longer, the teeth are all crenulated. Twelve specimens 

 from the Rio Puty. 



ANOSTOMUS ISOGNATHUS Kn. ; Gth. 

 A.. Knerii St. 



The lateral band, figured by Kner, appears to be quite 

 variable. Specimens from the Velhas show it still further 

 reduced than in the form figured as A. Knerii, it being 

 simply a black spot at the base of the caudal with faint 

 indications of continuation forward and backward. There 

 are five entire series between the lateral line and the ven- 

 tral, or seven between the line and the median ventral se- 

 ries. Mouth directed forward, jaws nearly equal, teeth 

 crenulate in the upper and lower. Snout about one and 

 one-half times as long as the eye. Depth three and two- 

 thirds and length of head four and one-fourth times in the 

 total length, without caudal. The row of scales from the 

 first ray of the ventral toward the hinder part of the dor- 

 sal passes entirely behiiu:! the latter. 



