84 REPORT OF NEAV JERSEY STATE MUSEUM. 



Order CHONDROSTEI. 



The Sturgeons. - 



Contains only the family of Sturgeons. 



Family ACIPENSERID^. 



The Sturgeons. 



Body elongate, subcylindrical. Snout produced, depressed and 

 subspatulate. Eyes small. Mouth small, inferior, protractile, 

 with thickened lips. No teeth. Maxillary distinct from premax- 

 illaries. Four barbels in a transverse series on lower side of 

 snout in front of mouth. Nostrils large, double, in front of eye. 

 Gills four and an accessory opercular gill. Gill-membranes united 

 to isthmus. No branchiostegals. Pseudobranchiae small or obso- 

 lete. Air-vessel large, simple, connected with oesophagus. Stom- 

 ach without blind sac. Pancreas divided into pyloric appendages. 

 Rectum with a spiral valve. Body armed with five rows of bony 

 bucklers, each with a median carina terminating in a spine which 

 sometimes becomes obsolete with age. A median dorsal series 

 and a lateral and abdominal series on each side, latter sometimes 

 deciduous, and between these skin rough with small irregular 

 plates. Head covered by bony plates joined by sutures. Fin 

 rays slender, all articulated and vertical fins with fulcra. Dorsal 

 placed posteriorly, anal somewhat behind it and similar. Tail 

 heterocercal, lower caudal lobe developed and upper covered with 

 rhomboid scales. Pectorals placed low. Ventrals many-rayed 

 and behind m.iddle of body. 



Large fishes of the seas and fresh waters of northern countries, 

 feeding on small animals and plants sucked in through the tube- 

 like mouth. The variation due to age is great and. together with 

 the individual variation has given rise to many nominal forms. 

 In our waters but two species referable to the genus Acipenser. 



