-j_24 The Philippine Journal of Science 1923 



coral reefs, our knowledge of the distribution of many species 

 is still very defective. Certain genera have been neglected by 

 collectors, while the fishermen fear and, therefore, make little 

 attempt to catch the large, fiercely biting, snakelike morays. 



In preparing this paper Jordan's Genera of Fishes and The 

 Fishes of the Indo-Australian Archipelago by Weber and 

 Beaufort have been of great assistance. No attempt has been 

 made to make the synonymy complete in all respects. 

 Order SYNBRANCHIA 

 This group of serpentlike fishes is of degraded type and un- 

 known relationships, but is probably closely related to the Apodes, 

 having the body naked or with minute cycloid scales. 



The mouth is of the ordinary fish type, the maxillary, pre- 

 maxillary, and palatine bones being well developed, while in the 

 typical forms the shoulder girdle is joined to the head; in one 

 family, the Amphipnoidse of India, it is distinct from the skull 

 as in the true eels. There are no paired fins, while the rudimen- 

 tary vertical fins are reduced to mere folds of skin. The gills 

 may be well developed or they may be rudimentary ; in the latter 

 case there is an accessory breathing apparatus, consisting of a 

 respiratory air sac or sacs in the neck, behind the head and 

 communicating with the gill cavity. The gill openings are con- 

 fluent in a single ventral slit. There is no air bladder, and the 

 stomach has neither a blind sac nor pyloric caecae. The skull is 

 solid, and the bones are firmly united ; the vertebrae are numerous, 

 unmodified, with ribs present; the anal opening is far back in the 

 posterior half, and the ovaries have oviducts. 



This order includes a small number of eel-like fishes widely 

 distributed in tropical fresh and brackish waters and along the 

 coasts of warm seas. Four families of divergent structure are 

 known ; representatives of two of them occur in the Philippines. 

 They are both scaleless, without accessory breathing apparatus, 

 and have the shoulder girdle attached to the skull. 

 Key to the families. 



a 1 . Gill arches three, gills rudimentary Monopteridse. 



a\ Gill arches four, gills well developed Synbranchidffi. 



MONOPTERIDSE 



RICE-FIELD EELS 



Body elongate, naked, tail short and tapering to a point ; mar- 

 gin of upper jaw formed by premaxillaries, the maxillaries well 



