SILURID^E. 



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

 the isthmus. 



Group R. A single maxillary barbel on each side. 



Stegophilina, p. 276. 



Synopsis of the Genera. 



First Subfamily. SILURID^E HOMALOPTER.E. 



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. Clarias, p. 13. 



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



Group B. Flotosina. 



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. 



Gill-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. 



Gill-membranes attached to the isthmus ... 5. Cnidoglanis, p. 27. 



Group C. Chacina. 



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

 dorsal and two anal fins. 



Nostril without barbel G. Chaca, p. 29. 



Second Subfamily. 



SILURID.E HETEROPTER.E. 



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

 ventrals below or behind the dorsal; gill-membranes entirely 

 separate, overlapping the isthmus. 



Group D. Silurina. 



a. Gill-c(ivity with an accessory sac posteriorly. 

 Adipose fin none 7. Saccobranchis, p. 30. 



