Henn: South American Pceciliid Fishes. 139 



Color in spirits, golden yellow. Margins of scales outlined with 

 darker. A conspicuous dark zig-zag line of chocolate pigment is 

 formed by the heavily pigmented upper margins of the scales in the 

 sixth lateral series, counting ventrally and transversely from the dorsal. 

 Then ext series of scales below forms a clear streak without pigment. 

 The keel of the caudal peduncle is also slightly pigmented. 



Named for Dr. W. J. Holland, whose interest and support has made 

 possible the extensive collections of South American fishes in the 

 Museum of which he is Director. 



Genus Fitzroyia Giinther. 



Fitzroyia Gunther, Cat. Fishes Brit. Mus., VI, 1866, pp. 299, 307 {mullidentata). 

 Jenynsia Gunther, ibid., VI, 1866, pp. 300, 331 (lineata). 



Type of genus by monotypy Lebias multidentata ] enyns = Lebias 

 lineata Jenyns. 



The dentition consists of an outer series of compressed, slightly 

 recurved, tricuspid incisors, immediately behind these a band of much 

 smaller tricuspid teeth. Intestine about equal to, or less than, the 

 length of the fish. 



Anal fin of the male modified to form a tube. Anal rays separate, 

 but enclosed in a loose sheath, forming the tube. The tip of this organ, 

 as pointed out by Carman, turns either to the right or left, the males 

 are thus rights and lefts. The genital orifice of the female is sym- 

 metrical. This fact seems to indicate that the male dextrality and 

 sinistrality, at least in this genus, has no especial significance. 



The male organ of this genus is much simpler than in Anableps. 

 In Anableps the anal rays are indeterminable, are heavily ensheathed 

 in fleshy pads and are scaled. The anal tubular structure may thus 

 have arisen independently in the two genera. 



Several young males of F. maculata show the development of the 

 tube. An epidermal flap appears, surrounding the foremost anal rays, 

 and eventually enclosing all of them. The anal tube of adult males is 

 about equal to the length of the head. 



Body slightly depressed; snout short and blunt; cleft horizontal; 

 lower jaw not extending beyond upper. 



Key to the Species of Fitzroyia. 

 a. Scales less than eighteen between occiput and dorsal. 

 b. Origin of dorsal slightly in advance of anal. 



c. Lateral line 29-30, a series of regular, longitudinal lines on the flank. 



32. lineata (Jenyns). 



