160 MARINE AND FRESHWATER FISHES 



the freshwater tanks in the Buckland Museum, which have 

 lived there in company with purely fluviatile species for a 

 period of several years. 



ORDER lll.Physostomi. 



All the fins rays articulated, excepting the first ray in 

 the dorsal and pectoral fins, which are frequently more or 

 less ossified. The bladder when existing, provided with a 

 distinct pneumatic duct 



FAMILY I. ARGENTINES OR SILVERSPOTS 

 (Sternoptychid<z). 



Margin of upper jaw formed partly by the premaxillary 

 and partly by the maxillary bones, both of which are 

 provided with teeth. Opercular bones not fully developed ; 

 rows of luminous eye-like spots developed along the lower 

 surface of the abdomen, and sometimes on other regions of 

 the body. 



Two small and rare species that naturally inhabit the 

 deeper waters of the ocean, but are occasionally washed 

 upon our coasts after stormy weather, have to be included 

 in the British list. These are the Half-armed Silverspots 

 (Argyropelecus hemigymnus\ No 141, and the Sheppy 

 Argentine (Maurolicus pennantii), No. 142. Both possess 

 in common those ventral rows of problematic structures 

 that, shining like burnished silver, have won for them the 

 popular title of "Silver Spots," and which in an allied 

 exotic form (Astronethes) have been demonstrated by 

 Professor Reinhardt to be endued with undoubted phos- 



