37 



To facilitate the discrimination of genera in case one can 

 dispose only of female or male specimens without a brood 

 organ, we give the following artificial key in which nearly 

 no use is made of the egg-bearing organ. 



Artificial key to the i n d o-a ust ralian genera 

 of Sy ngnathidae. 



I. Caudal fin present. 



1. Dorsal, anal and pectorals absent Penetopteryx p. 95. 



2. Pectorals absent Nannocamptis p. 94. 



3. Dorsal, anal and pectorals present. 



A. Superior cristae of trunk and tail discontinuous. 



a. Operculum without a keel ; inferior cristae of 

 trunk and tail discontinuous; median cristae of 

 trunk and inferior cristae of tail continuous. 



1. Dorsal 21 25. Subdorsal rings I -j- 3 4. 

 Edges of shields with a pronounced posterior 

 spine. Upper profile of snout scarcely sepa- 

 rated from forehead Acanthognathus p. 41. 



2. Dorsal 42 60. Subdorsal rings 4 5 rj- 8 9. 

 Edges of shields indistinct, rounded. Snout 



distinctly separated from forehead Coelonotus p. 56. 



3. Dorsal 64 68. Subdorsal rings n 12 -\- 4. 

 Edges of shields rounded, smooth. Upper pro- 

 file of snout gradually continued in that of 



forehead Belonichthys p. 59. 



b. Operculum with a complete or basal, incom- 

 plete keel. Inferior cristae of trunk and tail 

 continuous or discontinuous; median cristae of 

 trunk and inferior cristae of tail continuous or 

 discontinuous. 



aa. Opercular keel rectilinear. Base of dorsal not 

 elevated. 

 at. Trunkrings more numerous than tailrings. 



Dorsal for its greatest part inserted on 



trunk; caudal longer than half length 



of head Doryrhamphus p. 63. 



/3. Trunkrings equal to or generally less nu- 

 merous than tailrings. Dorsal for its greatest 



part inserted on tail ; caudal equal to or 



shorter than postorbital part of head. 



cuoe.. Egg-pouch abdominal. 



