VERTEBRATA: LITERATURE. 507 



ment-like teeth, are known, both from the Secondary and 

 Tertiary rocks. The last division of the Elasmobranchii 

 viz., that of the Holocephali is poorly represented in past 

 time by Mesozoic and Kainozoic genera such as Ischiodus, 

 Elasmodus, Ganodus, and Edaphodus. 



III. The order of the Dipnoi, until of late years, was not 

 known to be represented in past time at all. By the discovery, 

 however, of the Queensland Ceratodi, it is now known that the 

 Triassic and Jurassic teeth (fig. 274), upon which the genus 

 Ceratodus was originally founded by Agassi z, are truly refer- 

 able to Dipnoous fishes, mostly closely allied to the living 

 forms. No other form of the Sirenoid division of the Dipnoi 

 is known save Ceratodus ; but the Ctenodipterine division of the 

 order is well represented in past time by the Dipterus of the 

 Devonian, the Ctenodus of the Devonian and Carboniferous, 

 and some other less important genera. 



IV. The Bony or Teleostean fishes do not make their ap- 

 pearance sooner than the Cretaceous period that is, towards 

 the close of the Mesozoic epoch. From this time on, how- 

 ever, Bony fishes with cycloid or ctenoid scales are the chief 

 representatives of the whole class, and the order appears to 

 have attained its maximum in our present seas. 



LITERATURE. 



[In addition to many of the systematic treatises quoted in the list of 

 works dealing with the Vertebrata generally (p. 459) the student of recent 

 and fossil fishes may consult the following : ] 



1. " Histoire Naturelle des Poissons." Cuvier and Valenciennes. 1828- 



49- 



2. "Catalogue of Fishes in the Collection of the British Museum." 



Giinther. (Begun in 1859.) 



3. ' Allgemeine Naturgeschichte der Fische." Bloch. 1782-95. 



4. ' Atlas Ichthyologique." Bleecker. 1861-76. 



5. ' History of British Fishes. " Yarrell, 2d ed. 1836-60. 



6. ' History of the Fishes of the British Islands." Couch. 1865. 



7. ' Histoire Naturelle des Poissons d'eau douce de 1'Europe Centrale." 



Louis Agassiz. 1839-42. 



8. ' Anatomic des Salmones." Agassiz and Vogt. 1845. 



9. ' Histoire Naturelle des Poissons. " Lacepede. 1756-1826. 



10. ' Lehrbuch der Zootomie. " Von Siebold und Stannius. 



11. Article " Fishes " in Todd's ' Cyclopaedia of Anat. and Phys.' 1847. 



Rymer Jones. 



12. " Systematische Beschreibung der Plagiostomen." Miiller und Henle. 



1841. 



13. "Anatomic der Myxinoiden." J. Miiller. 'Abhandl. der Berlin 



Akad.' 1835-45. 



14. " Ueber den Bau und die Grenzen der Ganoiden." J. Miiller. Ibid. 



1846. 



