7 82 



COMPENDIUM OF GENERIC DISTINCTIONS. 



Family. MURVENIDjE. No pectorals ; gill-openings 

 only narrow slits. 



Genus. MUR./ENA. Single row of teeth on nasal bone. 

 Many seas. 



Family. GYMNOTID^E. No dorsal ; anal very long. 

 Gfttus. GYMNOTUS. -Scales none. 



Family. LEPTOCEPHALID^E. Small, scaleless, very 

 much compressed, and transparent. Lateral line formed by 

 intersection of muscles. Many seas. 



Genus. HYOPRORUS. Jaws long, straight ; body deep be- 

 hind head. Tail pointed. 



Genus. TtLURUS. Membranous dorsal beginning at head. 

 Anal none. Pointed teeth in both jaws. Tail very long. 



Genus. LBPTOCBPHALUS. Muscular bands bent regularly 

 forward. Tail moderate. 



Sub-order. A BDOMINA LES. Ventrals on abdomen 

 and behind pectorals, sometimes absent. Swimming-bladder 

 in most, and with an air-duct. 



Family. HETEROPYGIDjE. Ventrals small. Dorsal 

 set far back. Gill-apertures small. Body scaled. Teeth 

 small and sharp in palate, none on vomer or tongue. Bran- 

 chiostegals seven. Eyes none external. 



Genus. AMBLYOPSIS. As family. North America. 



Family. CLUPEID^E. Fatty dorsal wanting. Body 

 with distinct and mostly large scales. Two inferior pharyngeal 

 bones. 



Genus. ENGRAULIS. Head pointed, upper jaw longest, 

 gape very deep. Ventrals before dorsal. Branchiostegals 

 twelve. Many seas. 



Genus. CLUPEA. Body compressed, scales loose and large. 

 Teeth minute or wanting. One dorsal. Abdomen keeled. 

 Many seas. 



Family. ESOCID^E. Dorsal fin set far back, near tail- 

 fin. Edge of upper jaw partly formed by intermaxillary bone. 



Genus. EXOCSTUS. Pectorals large and very long, used 

 for flight. Lower lobe of tail-fin elongated. No teeth on 

 palate. Warm seas. 



Genus. HEMIRAMPHUS. Lower jaw long and projecting. 

 Teeth small and placed in a belt round each jaw, none on 

 palate. Body much elongated. Pacific. 



Genus. BELONE. Both jaws much lengthened and slender, 

 lower longer than upper. Teeth small in both jaws, of unequal 

 sizes. Many seas. 



Genus. Esox. Body rather long ; snout flattened. 

 Mouth, jaws, and palate, crowded with sharp teeth. Fresh 

 waters. 



Family. SALMONIDjE. Second dorsal of a fatty con- 

 sistence, without rays. 



Genus. SALMO. Head smooth. Teeth on vomer ; pala- 

 tine and maxillary bones. Branchiostegals often unequal on 

 the two sides. Seas and fresh waters. 



Genus. SCOPELUS. Teeth sharp and conical in both jaws. 

 Branchiostegals nine. Palatine teeth very small. Many seas. 



Genus. SERRASALMUS. Teeth in both jaws, triangular, 

 flat, sharp-edged, mostly in a single line. Body rather com- 

 pressed. Abdominal line serrated. Rivers of South America. 



Family. CYPRINIDONTID^E. Jaw-teeth very small. 

 Throat crowded with teeth. Branchiostegals five six. Whole 

 of head scaled. No fatty fin. 



Genus. ANABLEPS. Teeth on palate. Cornea of eye di- 

 vided transversely. Head flattened between eyes. Nostrils in 

 short tube. Surinam. 



Family. CYPRINID^E. Body with rounded scales. One 

 rayed dorsal. Mouth small and toothless. Inferior pharyn- 

 geal bones with large teeth. Branchiostegals three. 



Genus. CYPRINUS. Head naked. Branchiostegals flat and 

 broad. Anal fin short. Fresh waters. 



Genus. TINCA. Dorsal and anal fins short, 

 small. Scales small. Ponds and rivers. 



Barbules very 



Genus. ABRAMIS. No barbules. Body deep and com- 

 pressed. Base of anal long. Lakes and rivers. 



Genus. LBUCISCUS. Dorsal and anal short. Barbules 

 none. Fresh waters. 



Family. SILURIDJE. Body naked or shielded. In most 

 the first ray of dorsal and pectoral a spine with movable 

 joint. 



Genus. SILURUS. Body naked. Teeth very numerous. 

 Dorsal small, single near head. Anal long. Barbules four to 

 six, some very long. Seas and rivers. 



Order. PECTOGNATHL Upper jaw-bones immov- 

 ably joined to sides of intermaxillaries. Body with shields or 

 spines and scales. 



Family. SCLERODERML Snout conical or pyramidal. 

 Mouth toothed, in front of snout. Body with hard scales or 

 cuirassed. 



Genus. OSTRACION. Teeth ten to twelve in each jaw. 

 Body tri- or quadrangular, cuirassed, with holes for tail, fins, 

 and mouth. Tropical seas. 



Genus. BALISTES. Body compressed. Eight teeth in each 

 jaw. First dorsal formed of one or several spines. Second 

 dorsal near tail, soft. Tropical seas. 



Family. GYMNODONTES. Jaws projecting from mouth, 

 covered with solid tooth-ivory. 



Genus. DIODON. Jaws not divided. Warn. seas. 

 Genus. TRIODON. Upper jaw divided. Warm seas. 

 Genus. TETRODON. Both jaws divided. Warm seas. 



Genus. ORTHRAGORISCUS. Body very short, deep, and 

 compressed. Jaws not divided. Dorsal and anals connected 

 with tail-fin. Many seas. 



Order. LOPHOBRANCHIATA. Gills composed of 

 small round tufts, the operculum very large and the aperture 

 very small. Body covered with bony rings. 



Family. PEGASID./E. Breast very wide ; pectorals long, 

 with nine or ten spiny rays. Mouth below snout (like that of 

 the sturgeon). Breast-ring very broad, with two spines. Tail- 

 fin with ten strong rays. 



Genus. PEGASUS. As family. Warm seas. 



Family. SYNGNATHID/E. Body long. No first dorsal 

 or ventral. Anal very small or wanting. Males with egg- 

 pouch. Gill-aperture small and circular. 



Genus. HIPPOCAMPUS. Tail prehensile at tip, without fin. 

 Hind part of head elevated. Most seas. 



Genus. SYNGNATHUS. Snout long, cylindrical, without 

 spines. Body seven-sided. Most seas. 



Order. GANOLEPIDOTI. Body covered with strong, 

 bony, enamelled scales. 



Genus. LEPIDOSTEUS. Jaws long and narrow. Scales in 

 oblique rows, tending backward. Dorsal small and near tail. 

 Vertebrae extending to upper lobe of tail. North America. 



Order. CYCLOSTOMI.-Body cylindrical. Branchiae 

 with six or seven spiracles on each side. 



Family. PETROMYZONID^E. -Lip circular or horse- 

 shoe shape. Two dorsals. 



Genus. LAMPETRA (including Petromyzon). Mouth circu- 

 lar, with hard tooth-like processes. Branchial apertures seven. 

 No pectorals or ventrals. Seas and rivers. 



Genus. GEOTRIA. Skin of throat dilated into pouch. 

 Rivers, Australia. 



Genus. AMMOC<BTES. Lip of horseshoe shape. Mouth 

 not toothed. Rivers. 



Genus. M YXINE. Dorsal very long and broad, running round 

 tail. Lip surrounded with barbules. Mouth with a single 

 hook-like tooth, tongue with two rows of teeth on each side. 

 Branchial apertures two. Many seas. 



Order. LEPTOCARDII. Pulsating vessel instead of 

 heart; blood pale. Dorsal cord instead of vertebras. 



Genus. AMPHIOXUS. Body sharp at both ends. Dorsal 

 running round body. Mouth below, a mere longitudinal slit. 

 Many seas. 



