SILXJEID.E. O 



length of the body. Gill-membranes confluent with the skin of 

 the isthmus. 



Grouj) R. A single maxiUary barbel on each side. 



Stegophilina, p. 276. 



Synopsis of the Genera. 



First Subfamily. SILURID^ HOMALOPTER^. 



The dorsal and anal fins are very long, nearly equal in extent 

 to the corresponding parts of the vertebral column. 



Group A. Clariina. 



Gill-membranes entirely separate and free ; the dorsal is uniformly 

 composed of feeble rays, or its posterior portion is adipose. 



Dorsal fin without adipose portion 1 . Cl arias, p. 13. 



Two dorsal fins, the posterior adipose 2. Heterobranchus, p. 21. 



Group B. Plotosina. 



Gill-membranes free from the skin of the isthmus, or united with 

 it by a narrow strip only ; dorsal divided into two portions, the ante- 

 rior with a spine ; the posterior and the anal united with the caudal. 



GiU-membranes entirely separate and free from the isthmus ; head depressed. 



3. Plotosus, p. 23. 



Gill-membranes united anteriorly, but free from the isthmus ; head rather com- 

 pressed 4. COPIDOGLANIS, p. 25. 



GiU-membranes attadied to the isthmus ... 5. Cnidoglaxis, p. 27. 



Group C. Chacina. 



Gill -membranes confluent with the skin of the broad isthmus. Two 

 dorsal and two anal fins. 



Nostril without barbel 6. Ch aca, p. 29. 



Second Subfamily. 



SILURID^ HETEROPTER.E. 



Dorsal and adipose fins very short, if present ; anal very long ; 

 ventrals below or behind the dorsal ; giU-membranes entirely 

 separate, overlapping the isthmus. 



Group D. SUurina. 



a. Gill-awifi/ tvith an accessory sav posteriorli/. 

 Adipose fin none 7. Saccobranuh.s, p. 'M. 



