COELACANTHINI 289 



The skull is well ossified both outside and in (Figs. 259, 261, A). 

 The ossified prootics and opisthotics show that the cranium closely 

 resembled that of the lower Actinopterygii. The orbit is large, not 

 far forward, and surrounded by a ring of plates. The exact position 

 of the nostrils is unknown. There appears to be no separate row 

 of supratemporals ; and a peculiar series of small parafrontals passes 

 above the orbit towards the snout. The hyomandibular is closely 

 connected with the quadrate and pterygoid plate in a very Teleost- 

 like manner (Fig. 261, C). Teeth are distributed over the roof 

 of the mouth, small ones on the pterygoids and the expanded 

 anterior end of the parasphenoid, and larger teeth on the palatines 

 and vomers. The maxillae and premaxillae are toothed, but the 

 dentary is small and usually toothless. A large splenial bears the 



Two scales of Macropoma Mantelli, Ag. a, anterior smooth region ; d, denticle fixed on 

 posterior exposed region. 



teeth of the lower jaw. There are large paired gular plates, but 

 no lateral gulars, nor is any subopercular or preopercular found. 

 A large opercular is present. Post-orbitals cover the cheek. The 

 epihyal, ceratohyal, and five branchial arches are ossified, also a 

 median forked bone below, which may represent the basibranchials. 

 Clavicles, cleithra, and post-temporals (or supraclavicles ?) can be 

 made out in the dermal shoulder-girdle. The scales are thin, deeply 

 imbricated, and either cycloid or with a pointed posterior border. 

 They are composed of the usual inner bony layers, over which is 

 found in some genera (Coelacanthus) a striated enamel-like ornamenta- 

 tion of doubtful significance ; in other genera (Macropoma) the 

 exposed surface of the scales is studded with fixed denticles of 

 typical structure (Fig. 262). Similar denticles are found on the 

 lepidotrichia, and, in more or less modified form, on all the dermal 

 bones of the head (Williamson [496a]). 



The large air-bladder is conspicuous in fossil Coelacanths owing 

 to the calcification of its wall (Fig. 259). 



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