CEANIAL OSTEOLO&Y OF THE PHKACTOL^MIDiE. 277 



recent classificatory scheme of Teleosteau fishes (Ann. Mag. Nat. 

 Hist, (7) xiii. 1904, p. 164), has placed the Pantodontidae and 

 the Osteoglossidse together, but has separated the Hyodontidae 

 from them on account of the large size of their supratemporal 

 bone. 



Prom a study of the skull of Syodon (see Journ. Linn. Soc, 

 Zool. xxix. 1904, pp. 206-210), I am disposed to doubt whether 

 any close affinity exists between the Hyodontidae on the one hand 

 and the Pantodontidse and Osteoglossidse on the other ; but the 

 results of the present investigation fully justify the action takeu 

 by the ichthyologists named in closely associating the Panto- 

 dontidse with the Osteoglossidae. 



Phkactol^mid^. 



Phractol^mfs Ansoegii. 



The family Phractolsemidae (sole genus Phractolcdmus) is 

 described by Boulenger (Proc. Zool. Soc. 1901, i. pp. 5-7) as 

 occupying a position intermediate between the Osteoglossidae and 

 the Clupeidse. This is the reason why the consideration of the 

 skull of Phractolcemus is taken here : as will be seen later, the 

 skull bears no close resemblance to that of either family. The 

 skull examined is that belonging to a skeleton in the British 

 Museum marked " Fhractolcdmus Ansorgii, 1901, 1.28.4, Niger 

 Delta." Some of the more important characters of the sicull 

 have already been published by Boulenger in the paper above 

 cited. 



The cranium is broad, short, and depressed. The frontal 

 bones are very large, and in the specimen examined the right one 

 overlaps the left. The parietals are small and are widely 

 separated by the supraoccipital, which is broad and short. The 

 transverse commissure of the sensory-canal system passes from 

 parietal to parietal through the supraoccipital bone. Projecting 

 from the side of each exoccipital is a large rib which runs outward 

 and somewhat downward, and is attached by ligament to the 

 pectoral girdle. This cranial rib is in serial order with the 

 trunk ribs (although there are no ribs on the first and second 

 vertebrae), and differs from them in being straighter and shorter. 

 There are no Weberian ossicles, and there are no osseous bullae 

 for lodgment of csecal diverticula of the swim-bladder. Opening 



