<The Red Rivulus 



GEORGE S. MYERS 



The Xanthic Form of Rivulus urophthalmus 



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The golden Rivulus, perhaps more 

 commonly called the red Rivulus, is a na- 

 tive of Brazil, from whence it was taken 

 to Germany in 1911. There seems to be 

 some doubt as to the species of which it 

 is a color variety. References may be 

 found to it as Rivulus poeyi flava, and it 

 has been called R. harti. Stansch dis- 

 poses of it as a yellow-red form of R. 

 urophthalmus, which is probably correct. 

 The fish called R. poeyi by aquarists 

 when first imported, was later found to 

 be R. urophthalmus, which arouses a 

 doubt as to whether true poeyi has yet 

 been secured. 



.Leaving aside the question of identifi- 



cation, the fish seems to be an albinotic 

 (a xanthic) form. It does not seem to 

 have been determined whether it con- 

 tains more than the normal amount of 

 yellow pigment which in the presumed 

 normal species is masked by the melanin 

 or black coloring matter. The prevailing 

 color of the form is light orange-yellow, 

 with lengthwise rows of small vermillion 

 spots, the latter being more noticeable in 

 the male. The fins and eyes have a 

 greenish tinge. It reaches a length of 

 two and one-half to three inches. 



It breeds in a manner similar to other 

 egg-laying cyprmodonts, such as Hap- 

 lochilus, Fitiidiilus and so on. The eggs 



