380 MR. C. TATE REGAN ON [Apr. 10, 



** Depth of body 2-2f in the length 6. T. maculatus. 



/?. Lateral line wanting posteriorly ... 7. T. imilineatus. 



h. Praemaxillary teeth in a single series . 8. CJiirodon pulcher. 



2. Teeth wanting 9. Curimatiis argenteus. 



II. Body elongate, scaly; no ventral fins; no dorsal; anal 



very long 10. Carapus fasciatus. 



III. Body naked or with bony plates ventral fins present, 



abdominal ; an adipose tin. 



A. Body naked ; adipose fin normal. 



1. Gill-membranes with free posterior edge, not united to 



the isthmus. 



a. Adipose fin short. 

 Teeth on the palate in two small separate patches. 11. Arius spixii. 

 Teeth on the palate forming a broad continuous band. 



12. A. herzhergii. 



b. Adipose fin very long 13. Pimelodus ivilsoni. 



2. Gill-membranes broadlj' united to the isthmus. 



Caudal fin deeply forked 14. Pseudauch enipterus guppyi. 



Caudal fin obliquely truncate 15. Paraucheniplerus pasece. 



B. Body covered on each side with 2 series of lamella?, 



overlapping on the mid-lateral line ; adipose fin with a 

 movable spine. 



1, Two pairs of nuchal plates between parieto-occipital 



and basal shield of spine of dorsal fin. 



a. Coracoids not exposed on ventral surface. 



16. Callichtltys kneri. 



b. Coracoids exposed ventrally. 

 A median series of plates extending the whole of the distance 



from dorsal to adipose fin 17. C.Uttoralis. 



A median series of plates in front of the adipose fin, not extend- 

 ing forward to the dorsal 18. C. tlioracatus. 



2. Parieto-occipital produced into a process which reaches 



the basal shield of the spine of dorsal fin. 



19. Corydoras ceneus. 



C. Body covered on each side by 4 or 5 series of bony 



plates ; adipose fin with a movable spine. 



1. Upper surface of snout covered with small granular 



plates. 



a. Interoperculum little movable, not notably spinate 



or bristlj^ 



Eye moderate ; snout ovate 20. Plecostomus guacari. 



Eye small; snout broadly rounded 21. P. robini. 



b. Interoperculum freely movable, with a bunch of 



slender spines with hooked apices, which can be 



everted 22. Ancistrus trinitatis. 



2. Upper surface of snout naked, bearing prominent fleshy 



tentacles in the males 23. JCenooara cirrhosum. 



IV. Body elongate, eel-shaped, naked; no paired fins; gill- 

 openings represented by a single ventral slit. 24. Symhranchus marmoratus. 



V. Body elongate, enclosed in a series of bony rings ; no ventral 



tins; snout produced, tubiform 27. Doryichthys Uneatus. 



VI. Body scaly ; anterior part of dorsal fin formed of spines •. 

 or a separate anterior dorsal formed of spines or of simple ! 

 flexible rays. i 



A. Ventrals separate, each formed of an outer spine and of V 



five branched rays. \ 



1. A single dorsal fin. 

 Dorsal XVI-XVIII 7-8. Anal XIII-XIV 7-8... 33. Polycentrus schomburgkii. 



Dorsal XVII-XX 13-16. Anal III 8-10 34. Crenicichla saxatilis. 



Dorsal XIII-XIV 9-11. Anal III 7-9 Z5. Acarapulchra. 



Dorsal XIV-XV 9-11. Anal IV 8-9 36. CichlosQwa bimacwlatum. 



