of Puiciliid Fishes. 495 



presented by Herv J. Paul Arnold, one, Rivulus brevis from 

 Colombia, by Dr. W. WolterstorfF, and the fourth, Cyno- 

 lebias melanotcenia from Parauagua, by Herr A. Rachow. 



HlVULUS. 



Rivulus, Poey, Mem. Cuba, ii. 1861, p. ;507. 



Cynodonichthys, Meek, Publ. Columbiau Mus. Zool. v. 1904, p. 101. 



In. this genus the dorsal is shorter and further back than 

 the anal. D. 6-11. A. 8-17. The pelvic Hus are sniall. In 

 the typical species the head is depressed and the body i.s 

 subcyliudrical anteriorly, moderately compressed posteriorly ; 

 sometimes (e. g. R. brevis) the fish is compressed through- 

 out. 



Twenty-two species from Central and South America, 

 ranging from Cuba and Southern Mexico to the La Plata. 



Synopsis of the Species. 



I. 45 to 52 scales iu a longitudinal series. 



D. 10-11. A 14-16. Dorsal origin twice as disr 



tant from eye as from base ot caudal 1. jiertianus. 



D. 9. A. 16-17. Dorsal origin twice or more 

 than twice as distant from head as from base 

 of caudal 2. hohni<B. 



D. 8-9. A. 11-12 3. qcellatus. 



II. 36 to 42 scales in a longitudinal series. 



A. Anal ending below anterior part or middle of dorsal. 



1. D. 6-8. 



A. 11-13. Dorsal origin more than twice as disr 

 tant from bead as from base of caudal. 

 Caudal with ocellus in $ , without pale or 

 dark lower edge in J 4. urophthalmus. 



A. 12-15. Dorsal origin about twice as distant 

 from head as from base of caudal. Caudal 

 without ocellus in ^ > with dark lower edge 

 in c? 5. filegans. 



A. 11-12. Dorsal origin less than twice as dis- 

 tant from bead as from base of caudal. 

 Caudal with ocellus in g , with pale lower 

 edge and dark intramargiual stripe in cJ . . 0. godmani. 



A. 11-12. Dorsal orijiin more than twice as dis- 

 tant from head as from base of caudal. 

 Caudal as in R. (jodmaiii 7. tenuis. 



2. D. 9-10. A. 12-14 8. fabeUicauda. 



B. Anal ending below posterior part of dorsal. 



D. 10-11. A. 13 9. cylindraceus. 



D. 9. A. 14. Dorsal origin 2^ bead-lengths 



behind head 10. micropus. 



D. 8-10. A. 15-17. Dorsal origin less than 



2 head-lengths behind head 11. hartii. 



34* 



