222 CKANIAL ELEMENTS OF DAPEDIUS GBANULATUS. [June 1913, 



foramen between the prefrontal and the ethmoid, which gives- 

 access to the nasal fossa. 



In Lepidotus and Amia these nerves are entirely enclosed in 

 canals, but in Dapedius they are exposed for about two-fifths of 

 their passage across the orbit. 



On the outer side of the anterior opening for the olfactory nerve 

 is another passage between the nasal fossa and the orbit; this agrees 

 with the orbito-nasal foramen in Scyllium caniada, as shown by 

 Marshall & Hurst in their ' Practical Zoology,' through which enter 

 the anterior veins of the head communicating with the orbital sinus. 



Half way down the stout walls of the large opening between the 

 orbitospbenoids occurs on each side a small oblique oval foramen, 

 which probably gave access to the hyoidean artery into the cranium. 



The foramen magnum is high and compressed laterally, and 

 immediately below it the basioccipital is produced posteriorly in a 

 process above the notochord. This process is convex above, and 

 slightly hollowed on its inferior surface, the basioccipital on each 

 side also exhibiting a small condyle. 



Tbe only remaining foramina to be described are those for the 

 vagus nerves, which pierce the inferior surfaces of the exoccipitals ; 

 these are smaller openings than in Lepidotus, and have a more 

 downward direction. 



In conclusion, the cranium of the Ganoid Dapedius is shown to- 

 be more completely ossified than is the case with many Teleostei of 

 the present day. Tbe cartilaginous endoskeleton, as seen in Esoca 

 and the Salmonidee, is replaced by true bone ; and, although this 

 may remain cartilaginous internally, there is no outward evidence 

 that such is the case. 



In preparing this paper I have received much help from the 

 works of Dr. A. S. Woodward, F.B.S., and have also to acknowledge- 

 his kind personal assistance. 



Literature. 



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Journ. Morphol. vol. xii, p. 517. 1897. 

 ' The Cranial Osteology of Amia calva.' T. W. Beidge. Journ. Anat. & Physiol. 



vol. xi, p. 610. 1877. 

 'Histoire Naturelle ties Poissons d'Eau Douce de l'Europe Centrale.' L. Agassiz ; 



' Ernbryologie des Salmones ' by C. Vogt. PI. D, fig. 1. 1842. 

 'On the Anatomy of Vertebrates.' Sir Richard Owen. Vol. i, pp. 297-304. 



1866. 

 ' An Introduction to the Study of Fishes.' A. C. L. G. Gcnthee. Pp. 103, 112. 



1880. 

 'A Junior Course of Practical Zoology.' A. M. Marshall & C. H. Hubst. 



Pp. 221, 222. 1899. 

 British Museum (Natural History) Catalogue of Fossil Fishes. Part 3. A. S. 



Wood-wabd. P. 148. 1895. 

 ' On the Cranial Osteology of the Mesozoic Ganoid Fishes, Lepidotus & Dapedius: 



A. S. Woodwasd." Proc. Zool. Soc. 1893, pp. 559-65. 



