68 A Guide to the Zoological Collections 



and the outermost spine of each pectoral fin is enor- 

 mously enlarged and thickened and dreadfully barbed, 

 so as to form a formidable defensive weapon. In some 

 species [e.g. Plotosus) the wound inflicted by these 

 spines is as painful as the sting of a scorpion, and causes 

 a hurt that may be dangerous. The neighbouring 

 bones are specially strengthened for the support of these 

 great erectile spines. In Arius and Osteogeniosus the 

 males carry the fertilized ova in their mouths, probably 

 in order that the developing embryos may benefit by the 

 streams of fresh water as they pass into the gill-chamber 

 of the parent. In Exostoma, which lives in rapid 

 mountain streams, the lips form a sucker and the front 

 part of the belly forms a sort of adhesive pad, by 

 means of which the fish can attach itself to fixed 

 objects. Ckaca, which is not uncommon in the jheels 

 of Bengal, has the mode of life and much the external 

 appearance of a Frog-fish. In Saccobranchus (the Singhi) 

 each gill-chamber is prolonged to form a respiratory sack 

 that lies alongside the backbone, and enables this fish 

 to breathe out of water. In Glyptosternum which lives 

 in quick-flowing rivers, the pectoral fins are horizon- 

 tally expanded, and the surface between their bases is 

 pleated, to form an adhesive mooring apparatus. The 

 curiously wide distribution of the Siluroids has already 

 been commented upon. 



Family II. Scopelidce [Cases 70-71]. 



The members of this family are entirely marine, most 

 of them being either pelagic or living in the depths of 

 the ocean. One Indian species, the " Bummalo " or 

 " Bombay Duck," has a certain repute as food. The 

 genera may be noticed in detail. 



Genus 1. Scopelarchus, known only from the depths of 



