164 WELLBURN : FISH FAUNA OF YORKSHIRE COAL MEASURES. 
Genus : Ctenojjtychius Agassiz, 1838. 
Sp. C. apicalis Agassiz, 1838. 
Teeth not very common, but fairly well distributed. 
Genus: C allopristodiis Traquair, 1888. 
8p. C. pectinatus Agassiz, 1838. 
Teeth rare, distribution very limited. 
Sub-order : Atterospondyli. 
Family : Cochliodontid?e. 
Genus: Helodus Aga,sfiiz, 1838. 
Sp. //. simplex Agassiz, 1838. 
Teeth not rare, distribution not extensive. 
Genus : Fleuroplax A. Smith Woodward, 1889. 
Sp. F. Rankinei Handcock and Atthey, 1872. 
Teeth moderately common above the Better Bed Coal, but 
not common elsewhere. Distribution somewhat limited. 
Sp. P. Atthey i (W. J. Barkas, 1874). 
Teeth rare, distribution limited. 
Family : Cestraciontidie. 
Genus: Sphenacanthus Agassiz, 1837. 
Sp. S. hyboides (Egerton, 1853). 
Spines and Teeth : Spines common and fairly well dis- 
tributed ; teeth not common. 
Sp. *S'. cequistriatus Davis, 1879. 
Spines not common, distribution limited. 
Sp. *S'. minor Davis, lb79. 
Spines not common, distribution limited. 
Sp. S. sp. nov. 
Rare, distribution very limited. 
Order : Acanthodi. 
Family : Acanthodidye. 
Genus : Acanthodes Agassiz, 1833. 
Sp. A. Wardi Egerton, 1866. 
Fragmentary remains moderately common and well distributed. 
