EIGENMANN: THE FRESHWATER FISHES OF BRITISH GUIANA 113 



Th? difference between the male and female of Poecilocharax are indicated on 

 Plate XLIV, figures 1 and 2. 



In some of the Loricariidie the male is more abundantly supplied with spines. 

 In Pseudancistrus barbatus, for instance, the cheeks of the males are provided with 

 long bristles. In Lithoxus lilhoides the pectoral spines are much longer in the 

 male (Plate XXIX, fig. 4) than in the female (fig. 3) and more profusely provided 

 with bristles. 



The peculiar barbels, much more profusely developed on the head of the male 

 Ancistrus than on the female, have long been known (Plate XXV, fig. 3). 



New Genera and Species. 

 The new genera described during the progress of the work are: 



1. Chamaigenes. 15. Paecilobrycon. 



2. Agmus. 16. Archicheir. 



3. Megalonema. 17. Poecilocharax. 



4. Microglanis. 18. Aphyodite. 



5. Brachyglanis. 19. Dermatocheir. 



6. Leptoglanis. 20. Camegiella. 



7. Myoglanis. 21. Acanthocharax. 



8. Chasmocranus. 22. Heterocharax. 



9. Tympanopleura. 23. Gymnorhamphichthys. 



10. Lithogenes. 24. Porotergus. 



11. Corymbophanes. 25. Rhinosardinia. 



12. Lithoxus. 26. Tomeurus. 



13. Bivibranchia. 27.- Acarichthys. 



14. Tijlobronchus. 28. Soleonasus. 



The new species of fresh-water fishes, based on the collections made, are: 



1. Bunocephalus amour us. 14. Chasmocranus brevior. 



2. Bunocephalus chamaizelus. 15. Pimelodella megalops. 



3. Agmus lyriformis. 16. Pimelodella macturki. 



4. Megalonema platycephalum. 17. Pimelodus heteropleurus. 



5. Pseudopimelodus villosus. 18. Leptodoras linnelli. 



6. Pseudopimelodus albomarginatus. 19. Hemidoras microstomia. 



7. Microglanis poecilus. 20. Hemidoras micropaeus. 



8. Brachyglanis frenata. 21. Hemidoras leporhinus. 



9. Brachyglanis 7nelas. 22. Hemidoras notospilus. 



10. Brachyglanis phalacra. 23. Auchenipterus demerara. 



11. Leptoglanis essequibensis. 24. Auchenipterus brevior. 



12. Myoglanis potaroensis. 25. Tympanopleura piperata. 



13. Chasmocranus longior. 26. ^IgeneiosMS guianensis. 



