508 FISHES. 



FiSTULAElA. — Body scaleless ; caudal fin forked, with the 

 two middle rays produced into a filament ; no free dorsal spines. 



Three species are known, common on the shores of the 

 Tropical Atlantic {F. tabaccaria) and Indian Oceans {F. 

 serrata and F. depressa) ; they attain to a length of from four 

 to six feet. 



The anterior portion of the vertebral column shows the 

 same peculiarity as in Dadylopterus ; it is a long compressed 

 tube, composed of four elongate vertebree, which are per- 

 fectly anchylosed ; each of them has a pair of small foramina 

 for blood-vessels. The neural spines and parapophyses of 

 this tubiform portion are confluent into thin laminae, the 

 lateral of which are wing-like, and expanded in their anterior 

 half. 



AuLOSTOMA. — Body covered with small scales. Caudal fin 

 rhombic, without prolonged rays ; a series of isolated feeble 

 dorsal spines. Teeth rudimentary. 



Two species from the Tropical Atlantic and Indian 

 Oceans. 



AULISCOPS. — Body naked. Ventrals thoracic. Numerous 

 spines in front of the dorsal fin. 



One species {A. spinescens) from the Pacific coast of North 

 America. Aulorhynclius from the same sea, and Aulichthys 

 from Japan, are allied genera. 



Thieteenth Division— Acanthopteeygii Centeiscifokmes. 



Two dorsal fins ; the spinous short, the soft and the anal of 

 moderate extent. Ventral fins truly abdominal, imperfectly 

 developed. 



This division consists of one family, Centriscidm, with two 

 genera. The fishes belonging to it are very small, marine, 

 and, in consequence of their limited power of swimming, 

 often driven out into the open sea. They have the same 



