68 CAKL. L. HUBBS 



only one which distally bifurcates" (Jungersen, '10). In other 

 respects also the hyoid apparatus of the Lophobranchii is reduced, 

 probably from a condition like that of Fistularia. 



The Symbranchia were long considered a group of true eels, 

 but lately have been accorded a distinctly higher position. The 

 character of the branchiostegals are in harmony with the latter 

 view. In Monopterus javanensis, the rather narrow hyoid arch 

 bears two groups of slender branchiostegals: an upper cluster of 

 four and a lower inner pair, widely separated from the others. An 

 essentially similar condition is developed in Symbranchus mar- 

 moratus, but in this species the two groups of branchiostegals are 

 less widely separated. 



The curious Opisthomi (Mastacembelidae) of southern Asia and 

 Africa have been variously located in the teleost series; lately 

 Boulenger and Regan agree in placing them among the higher 

 teleosts, considering them as bearing a relation toward the spiny- 

 rayed fishes analogous to that which the Apodes bear toward the 

 soft-rayed group. This view is sustained by the branchiostegals 

 in Mastacembelus pancelas. From the outer surface near the 

 lower edge of the ceratohyal and epihyal, along the upper widened 

 portion of the hyoid arch, four rays arise in close proximity; they 

 are curved upward posteriorly, as in some of the Apodes, between 

 the operculum and the branchial aperture; on the inner surface 

 of the arch, near the concave anterior ventral margin, the two 

 lower anterior rays are inserted. 



The Salmopercae, long considered as intermediate between the 

 soft-rayed and spiny-rayed fishes, have six branchiostegals, 

 arranged exactly as in the Acanthopteri. Both of the species 

 usually referred to this group, Percopsis omisco-maycus and 

 Columbia transmontana, have been examined. Aphredoderus 

 sayanus, referred by Regan to the same group, has branchiostegals 

 in all essential respects similar to those of Percopsis and the 

 following groups. 



A definite fixed type of branchiostegal structure has been 

 retained, almost without deviation, throughout the great groups 

 of spiny-rayed fishes which flourish so abundantly in the modern 

 seas, and with peculiar constancy in the numerous highly special- 



