98 



aquatic Hilt 



Since 19 12 we have received — always 

 from Germany, and never direct from the 

 native country — sundry other varieties or 

 forms of Xiphophorus: X. jalapae, recog- 

 nized by the rich orange-red single lateral 

 stripe on the male, and paler yellowish- 

 orange stripe on the female (the single 

 stripe of helleri is more a brownish-red) ; 

 X. rachovii, a form from Guatemala with 

 a double red stripe on the sides of both 

 sexes, several narrow blackish vertical 



bles brevis, but has a blackish blotch at 

 the base of the tail, as in rachovii. Only 

 the male swordtails, with very few ex- 

 ceptions, possess the extension of the 

 lower rays of the tail-fin, from which 

 they derive the common name. So much 

 for the outward markings and colora- 

 tions of the forms with which we are 

 familiar. The distinctions I have given 

 will serve to identify the ones apt to be 

 met. 



Topical S'eJordtail (upper) and Two Variants 



stripes, and a blackish double spot or 

 "half moon" mark at the base of the tail ; 

 X. strigatus with a blackish lateral line 

 from the eye to the tail (this form is but 

 little known to aquarists) ; X. brevis 

 suggests hybridization with Platypoe- 

 cilus, as it has a number of blackish 

 blotches on the sides, an almost total ab- 

 sence of the lateral stripes so conspicu- 

 ous in the others, a yellowish "sword" of 

 noticeable shortness in the male fish ; 

 X. montezumae comes from the basin 

 of the Rio Panuco, Mexico, and resem- 



Any of the aforesaid forms can be 

 easily crossed with another, and indeed 

 with the various forms of Platypoecilus, 

 as has already been done by many of us, 

 so I think that we can rest assured that 

 they are not distinct and valid species. 

 The differences are not specific, and are 

 probably due to environment. Any 

 aquarist can make interesting studies of 

 hybridization in his aquaria, and should 

 report results, with photographs if pos- 

 sible, to the editor of this magazine. All 

 are easily bred and reared in well -planted 



