588 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



THE OGCOCEPHALIDS OR MALTHIDS. 



The family Ogcocephalids, or bat fishes, is in some respects, at least, 

 the most distinctly differentiated family of the Pediculates. The 

 head is large and much depressed, and, in most of the species, pre- 

 sents considerable superficial appearance to that of the anglers, but 

 the branchial apertures are in or behind the upper (and not lower) 

 axils of the pectorals; those fins are strongly geniculated, and the 

 elongated pseudobrachia have each three actinosts; ventral fins are 

 well developed and jugular; the first dorsal is obsolete or represented 

 by a single " rostral tentacle " which may be deflected downward 

 by the horizontal extension of the forehead; the soft dorsal and 

 anal fins are very short and few-rayed (D. 4—7, A. 3^), and in one 

 genus {Halicmetus) the dorsal is entirely suppressed. 



The most remarkable feature of the osteology is the great develop- 

 ment of the opercular apparatus, which is correlated with the supe- 



PiG. 29. — Skeleton of a Malthid (MaJilioi)sis aiuniilosa). After Garraan. 



rior position of the branchial apertures; the operculum and sub- 

 operculum are connected in a triangular plate expanding and pro- 

 longed backward and downward. 



For a long time the only genera of the family known were Ogco- 

 cephalns or Malthe from the American coast and Ilalieuta'a from the 

 China-Japanese waters. Later explorations, however, have brought 

 to light over thirty species representing as many as twelve genera. 

 Only three species of Ogcocej)lmlus and one of Halieutam are in- 

 habitants of shoal waters, all the others being deep-sea fishes, occur- 

 ing mostly at depths between 100 and 500 fathoms. 



The family has been disintegrated into two subfamilies, Ogcocepha- 

 lines, or Maltheines, and Halieuta^ines, but they run into each other. 



The typical Ogcocephalines are distinguished from all other fishes 

 by a unique character. The forehead is produced into a nearly hori- 

 zontal process which is so extended as to deflect the rostral tentacle 

 (a vestige of the first dorsal fin) so that it is actually directed down- 



