ggS class pisces. 



tines and ectopterygoids ; and the dentary bone of the mandible 

 has one series of large teeth, with one or more inner rows of smaller 

 ones. The type genus Enchodus, with which Eurygnathus of the 

 Lebanon beds is identical, occurs in the Upper Cretaceous of 

 Europe, North America, Brazil, and perhaps India. Closely allied 

 to this genus is Eurypholis (fig. 936), of the Lebanon Chalk, which 

 is merely distinguished by the presence of a few dermal scutes. 

 Cimolichthys, from the Upper Cretaceous of Europe and the United 

 States, and Pomognathus (Phylactocephalus), from the Chalk of 

 Europe and the Lebanon, are nearly related genera, mainly distin- 

 guished by their dentition. Here also may be placed Ischyrocepha- 

 lus, of the Upper Cretaceous of Westphalia, which may perhaps 

 have had two dorsal fins, and appears to connect Enchodus with the 

 Dercetidtz. 



Family Pachyrhizodontid^e. — Allied to the preceding, but with 

 the body more compressed, and covered with either scutes or scales, 

 or both together, is a group of Fishes which may be provisionally 

 placed in a distinct family. The premaxillae and maxillae are large, 

 and carry powerful teeth, which may form one or more rows, and 

 are set in incomplete sockets, and anchylosed to the bone ; while 

 the abdominal vertebrae are characterised by their longitudinal 

 striation and the absence of deep pits. The type genus Pachyrhiz- 

 odus {Hypsodon in part) ranges in Europe from the Chalk to the 

 London Clay, and also occurs in the Cretaceous of North America ; 

 its teeth are so like those of Reptiles that a lower jaw was described 

 as belonging to a species of Mosasaurus. E??ipo, of the North 

 American Cretaceous, may be certainly placed in this family ; in 

 which we may also probably include Stratodus, of the Upper Cre- 

 taceous of both Europe and North America. An allied type, from 

 the Lower Miocene of Belgium, has been described under the pre- 

 occupied name of Amphodon. 



Family Saurocephalid^: (Saurodontid^e). — The last family of 

 the Saurodonts are laterally compressed Fishes, in which the maxillae 

 and premaxillae are large, and carry powerful teeth, which are usually 

 implanted in distinct sockets. The dentary bone of the mandible 

 has but a single row of similar teeth, and there are no teeth on the 

 palatines and ectopterygoids. The vertebrae, with the exception of 

 those of the cervical region, carry two deep grooves and pits on 

 their lateral surfaces. The type genus Saurocephalus is represented 

 in the Cretaceous of North America, and also by a single species in 

 the topmost Cretaceous of Maastricht, in Holland ; the teeth are 

 subequal and closely approximated. Ichthyodectes and Portheus 

 (fig. 937) also occur in the Upper Cretaceous of both Europe and 

 North America ; the latter, which extends down to the Gault, attain- 

 ing large dimensions, and being characterised by the great crest in 





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