DEV'ONIC FISHES OF THE NEW YORK FORMATIONS II 5 



process in Phlyctaenaspis, Acanthaspis etc. At the same time it is worthy 

 of remark that both in form and position it is not wholly dissimilar to the 

 rodlike opcrciiluni iiifcriiis, as Fiirbringer calls it, of Neoceratodus. This 

 author's observation that the two opercularia of the recent form are some- 

 times fused into a single piece acquires significance on recollecting that 

 only a single opercular element is known to occur in most Arthrodires.' 

 Jaekel is the only author who has reported the occurrence in Coccosteus of 

 two opercula, this being the normal number amongst Dipnoans, as already 



stated. 



Genus coccosteus Agassiz 



Of the four American species that have been referred to this genus, 

 only one, C. canadensis Woodward, is satisfactorily known, the others 

 being represented by detached plates exclusive of the head shield. To C. 

 occidentalis, described in the first instance by Newberry from the 

 Corniferous limestone of Ohio, are possibly to be referred a few isolated 

 fragments occurring in the New York Mesodevonic, and it has been further 

 surmised by the original author that the dental plates known as Liognathus 

 spatulatus belong to the same species. In plate 9, figure 3, the dorso- 

 median plate of the type specimen is refigured to show the continuation of 

 sensory canals over part of its surface, their presence having escaped New- 

 berry's attention. No figures have been published of the form described 

 by Cope from the Chemung of Leroy, Pennsylvania, under the name of C. 

 macromus, but it is said to be distinguished from C. occidentalis 

 by its coarser tuberculation. 



In plate i, figure 9, is shown a dorsomedian plate of a small Coccostean 

 fish from the Onondaga limestone of Clifton Springs, N. Y., the original of 

 which is preserved in the State Museum at Albany [cat. no. 181]. A small 

 portion of the bone substance is preserved intact on the right-hand side, 

 and shows a coarsely tuberculated ornament. The remainder of the plate 

 is broken away, leaving an impression of the under surface. There is also 

 visible a strong longitudinal keel which extends along the median line, but 



' Fiirbringer, K. Beitrage zur Morphologic des Skeletes der Dipnoer etc. Semon's 

 Zool. Forschungsreisen in Australien. Jena Denkschr. 1904. 4:493. 



