86 



Aquatic JUte 



scratch. In assembling, therefore, the 

 proper name of the fish, the oldest genus 

 is Fitzroyia, and the oldest specific name 

 is that of the original author, so the 

 proper name according to the law of pri- 

 ority is Fitsroyia lineata. This has been 

 recognized by Berg (Annals of the Na- 

 tional Museum, Argentina) and by our 

 American ichthyologists Eigenmann and 

 Henn. English systematists — Regan and 

 Boulenger — seem to prefer Jenynsia. 



So far as I know this species has never 

 been brought to the United States. The 

 Germans secured it in 1905 but allowed 

 it to die out within a few years. A writer 

 of an interesting article, in one of their 

 magazines in 19 10 expresses great regret 

 at its disappearance. It has the distinc- 

 tion of being the "farthest south" vivip- 

 arous fish, ranging from the La Plata 

 to the Rio Grande do Sul, Argentina Re- 

 public. It is not, however, the only mem- 

 ber of the geus occurring in southern 

 South America. 



It is said that the streams it inhabits 

 are reasonably cool, which would make 

 it a desirable fish for those not having: 

 facilities for providing the extreme and 

 constant heat demanded by some exotic 

 fishes. It seems to be quite a large spec- 

 ies. German authors giving the length of 

 a female as 12 centimeters (about four 

 and three-fourth inches), but Henn notes 

 that the largest female in the collection 

 of the Indiana University Museum meas- 

 ures 69 millimeters ( less than three 

 inches). In the male, writers agree in 

 giving its length as up to 45 millimeters 

 (less than two inches). Fitzroyia is 

 unique among viviparous fishes studied 

 in aquaria in that the anal fin is modified 

 into an actual tube for the transmission 

 of sperm. The one other genus in which 

 the anal is tubular, Anableps, has not 

 been studied in aquaria, and its decribed 

 habits indicate it as entirely unsuitable. 



Our subject has another peculiarity, the 

 tip of the anal being bent either to the 

 right or to the left, males thus being 

 rights or lefts. This male dextrality and 

 sinistrality seems to have no significance 

 (in this genus) as the genital orifice of 

 the female is symmetrical. In certain 

 other fishes the females are also rights 

 and lefts, the orifice being protected by 

 a process making it necessary for a right 

 female to mate with a left male and vice 

 versa. 



The coloration is quite suggestive of 

 Mollienisia latipinna. The back is 

 brownish olive, passing to silvery gray on 

 the sides, with the lower parts white. 

 The sides have a decided light blue lustre 

 and four or five horizontal rows of black 

 dashes The dorsal region of the male in- 

 clines to blue-green, while the female is 

 rather brownish. 



In common with more familiar fishes 

 that bring forth living young, in the pres- 

 ent species the period of gestation has 

 been determined as lasting from four 

 to six weeks, temperature being appar- 

 ently the determining factor. The young 

 are few in number, considering the size 

 of the parent, a female bred in Germany 

 giving from twelve to thirty young in a 

 litter, which, however, were quite large 

 at birth, some measuring nearly three- 

 fourths of an inch in length. It is amus- 

 ing to note that the confusion in the 

 names has been carried down practically 

 to the present day. An aquarium book 

 mentions both but not as synonyms, one 

 being given as viviparous or live-bearing 

 while the other is disposed of as ovipar- 

 ous or egg-laying ! 



While the fish is unknown in our col- 

 lections, it seems to the writer that it 

 should not be hard to secure if the proper 

 efforts were put forth when steamship 

 service with South America becomes bet- 

 (Concludcd on page 90) 



