CYPRIXODONT FISHES. 979 



is of some interest to note that in Pcecllia and related genera 

 the females welcome the attentions of the males and the intro- 

 mittent organ is quite short, but as in Gambusia and Phcdloceros 

 the females try to make the males keep their distance it is 

 much longer. 



Synopsis of the Genera *. 



I. Lower edge of caudal peduncle sharp, without a 

 median series of scales ; boues of lower jaw firmly 

 united ; teeth conical or villiform. 

 Bodj' rather deep ; pelvic fins well developed, behind base 

 of pectorals ; anal tin of male without long appen- 

 dages 1. Alfaro. 



Body elongate ; pelvic fins absent in female, minute and 

 below gill-openings in male ; anal fin of male ending 

 in a pair of long appendages with spine-like processes 2. Tomenrns. 



II. Lower edge of cavidal pedmicle rounded or obtuse, 

 with median series of scales. 

 A. Pelvic fins similar in both sexes. 



1. First produced ray of anal fin of male without 

 long processes or appendages. 



a. Third and posterior branch of second pro- 



duced ray of anal fin of male each ending 



in a retrorse spine or hook. 

 Jsws not produced ; teeth conical or villiform ; anal fin 

 of male with distal part of first produced ray serrated, 

 the terminal serrations directed towards its tip ; 

 third produced ray and posterior branch of second 

 each ending- in a retrorse hook. Dorsal 6-12 ; origin 



behind that of anal 3, Oamhnsia, 



Jaws produced ; teeth slender, pointed, depressible ; anal 

 fin of male with terminal segments of first produced 

 ray not forming serrations ; third produced ray and 

 posterior branch of second each ending in a i-etrorse 

 spine....'. 4. Belonesox, 



b. Third and posterior branch of second pro- 



duced rays of anal fin of male not bearing 

 reti'orse hooks or spines, 

 a. Anal fin of male ending in a more or less 

 distinct antrorse hook, the anterior branch 

 of the second prodaced ray curved for- 

 ward. 

 * Mouth moderate, with distinct lateral 

 cleft ; teeth conical or villiform, 

 t Dorsal 7-12 ; origin behind that of anal. 

 Extremity of anal fin of male supported equally by third 



and anterior branch of second produced rays 5. Priapichtht/s, 



Extremity of anal fin of male supported equally hy first 



and anterior branch of second produced rays 6. Pruipellu. 



ft Dorsal 11-17 ; origin in advance of 

 that of anal ; extremity of male anal 

 fin a strong hook formed by the un- 

 segmented end of the anterior branch 



of the second produced ray 7, Pseudo.viphoj>ho)'us, 



** Mouth small, without distinct lateral 

 cleft; hook at end of anal fin of male 

 formed by anterior branch of second 

 produced ray. 



* The differences in the structure of the male intromittent organ used in this 

 synopsis are illustrated in text-figs. 168, 169 (genera 1 to 4 and 11), 170 (genera 5 to 

 10), 171 (genera 10 and 13), 172 (genera 14 to 22), luid 173 (genera 23 to 26). 



