380 MK. C. TATE REGAN ON [^P^'- 10, 



** Depth of body 2-2f in tlie length 6. T. maciilatus. 



/3. Lateral line wanting posteriorly ... 7. T. uniUneatus. 



h. PraBmaxillary teeth in a single series . 8. Chirodon pidcher. 



2. Teeth wanting 9. Curimatus argenfcus. 



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



very long 10. Carapus fasciatus. 



III. Body naked or with bonj'^ plates ventral fins pre.sent, 



abdominal ; an adipose fin. 



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 spi.vii. 

 Teeth on the palate forming a broad continuous band. 



12. A. hcrzbcrgii. 

 h. Adipose fin very long 13. Fimelodus wilsoni. 



2. Gill-membranes broadly united to the isthmus. 



Caudal fin deeply forked 14. Fseudaurhenipfertts gappy i. 



Caudal fin obliquel}^ truncate 15. Farauvhenipteriis pasca. 



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



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. Callichflij/s kneri. 



b. Coracoids exposed ventrally. 



A median series of plates extending the whole of the distance 



from dorsal to adipose fin 17. C. Jittoralis. 



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

 ing forward to the dorsal 18. C. tJioracatus. 



2. Parieto-occipital produced into a process which reaches 



the basal shield of the spine of dorsal fin, 



19. Corydoras aiicus. 



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 notablj'^ spinate 



or bristly. 



Eye moderate ; snout ovate 20. Plecnstomus ijuacari. 



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



b. Interoperculum freely movable, with a bunch of 



slender spines with hooked apices, which can bo 



everted 22. Ancistrus trinitatis. 



2. Upper surface of snout naked, bearing prominent fleshy 



tentacles in the males 23. Xenocara cirrhosum. 



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

 openings represented by a single ventral slit. 24. Symbranclius ma nun rat us. 



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



fins; snout produced, tubiform 27. Doryichthys lineatas. 



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

 or a separate anterior dorsal formed of spines or of simple 

 flexible rays. 



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

 five branched rays. 

 1. A single dorsal fin. 

 Dorsal XVI-XVIII 7-8. Anal XIII-XIV 7-8... 33. Polycentt-us sclwmhurgkii. 



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



Dorsal XIII-XIV 9-11. Anal III 7-9 35. Acarapulchra. 



Dorsal XIV-XV 9-11. Anal IV 8-9 36. Cichjo^pjna bimaoulatum. 



