SEX-CHARACTERS IN LEBISTES RETICULATUS. 375 



The Lebistes female, even if its X-chromosome contains genes of 

 color characters, does not phenotypically exhibit the latter. 



II. DESCRIPTION OF MATERIAL AND METHODS. 



In connection with genetic researches on Lebistis reticulatus I 

 had the opportunity to observe a great many of those little fishes 

 in the Moscow aquaria. Among the members of this species as 

 well as among members of other species which have come under 

 my observation I very seldom met with divergencies from usual 

 dimorphisms. 



My material consists of seven fishes, six of which are males 

 with marked divergence from typical dimorphism. The seventh 

 is a case of hermaphroditismus glandularis. The malformation 

 of dimorphisms of the males were either inborn or developed later 

 in the life of the individuals. Two males, No. 25 and No. 34, 

 belong to the former class. 



1. Male Fish No. 25. The individual measured 37 mm. in 

 length. It was entirely deprived of dimorphic colorations. The 

 shape of the body resembled that of a female. Upon dissection, 

 after the fish died, it was discovered that the testis was entirely 

 atrophied. 



2. Male Fish No. 34. It was born on the 5th of August, 1924. 

 On the 5th of May, 1925, when the animal was nine months old, 

 it measured 23 mm. in length but failed to exhibit any sex- 

 colorations. The gonopod was normally developed. Sex in- 

 stincts were not lacking ; repeated mating to fecundate females, 

 however, proved a failure. No sign of a gonad was discovered 

 macroscopically. 



3. Male Fish No. 23. This animal reached maturity in the 

 first part of September, 1924. Up to February of the following 

 year it remained quite normal as to dimorphic colors and sex- 

 instincts. During February the characteristic red spot on the 

 side of the body disappeared and the fish became almost colorless. 

 It died on the 27th of May, 1925, and on dissection revealed 

 entirely atrophied gonads (Figs. I and ia). 



4. Male Fish No. 8. With normal dimorphism this animal 

 reached maturity in August, 1924. Paleness of sex-colors was 

 noticed in March, 1925. On April of the same year both of the 



