Cockerell: Scales of Characinid Fishes. 97 



Tylohranchia maculosa Eigenmann (cotype). Plate XXV'I, fig. 2. 

 The figure shows the form of the scale, which is about six and one- 

 half mm. broad. The radial system is reduced to a single very 

 strong line crossing the scale, as in Bryconamericus. Base crenate; 

 basal and lateral circuli fine, the latter longitudinal (herein quite 

 different from Bryconamericus) ; nuclear field very broadly pustu- 

 lose; apical field without circuli; apical margin with low teeth. 

 This may also be compared with Tetragonopterus, but the direction 

 of the lateral circuli is entirely dift'erent. The closest resemblance 

 is evidently to Chilodus, which must surely be a close relative. 

 In the shape of the scale and the direction of the lateral circuli, 

 there is a curious resemblance to Tilapia nilotica, but the latter 

 has a regular system of fan-like basal radii or grooves. 



Gymnocharacinin.e. 



The single species is unknown to me. It has no scales. 



Anostomatin-e. 



The scales of Leporinus are of the Curimatoid shape, but usually 

 narrower, with a strong tendency to polygonal areas in the discal 

 region, and a deep median basal notch. The radii are usually distinct, 

 but not numerous. The circuli resemble those of Alestes sadleri, with 

 a consequent slight tendency to apical teeth, as in some Alestes. The 

 relationship with the Alestoids seems evident, in spite of the different 

 habits and important adaptive modifications. The following have 

 been examined: 

 Leporinus friderici Bloch. Scale shown in Plate XXVI, fig. 3. The 



photograph is unfortunately too dark to show the polygonal discal 



areas, with distinct apical and imperfect basal radii leaving them. 



The apical circuli slope obliquely toward the centre. There is in all 



this a very strong resemblance to the radial system of the Asiatic 



cyprinid Barhus pleurotccnia. 

 Leporinus megalepis Giinther. Scales similar to those of L. friderici, 



but the polygonal areas are less developed, and there are few but 



strong basal radii. 

 Leporinus fasciatus (Bloch). Scales rather long, the basal' radii 



imperfect, the apical ones numerous, and the oblique apical radii 



strong. Thus the scale comes to quite closely resemble that of the 



Asiatic Cyprinid Cirrhina jiiUieni. 



