186 IOWA GEOLOGICAL SURVEY 



toral limb. As shown by Furbringer,* the two opercular plates 

 of Neoceratodus are sometimes fused into a single piece, and this 

 fact acquires significance on recollecting that only a single oper- 

 cular element is known to occur in most Arthrodires. Jaekel is 

 the only investigator who has reported the presence in Coccos- 

 teus of two opercula, the normal number among Dipnoans, and it 

 would be interesting to have this observation confirmed. 



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 exclu- 

 sive of the headshield. To C. occidentalism described in the first 

 instance by Newberry from the Onondaga limestone of Ohio, 

 are possibly to be referred a few isolated fragments occurring in 

 the Middle Devonian of New York State, and it has further been 

 surmised by the original author that the dental plates known as 

 Liognathus spahdatus belong to the same species. No illustra- 

 tion has been published of the form described by Cope from the 

 Chemung of Leroy, Pennsylvania, under the name of C. macro- 

 mus, but it is said to be distinguished from C. occidenUxlis by 

 its coarser tuberculation. A restoration of the type species of 

 this genus is given in the accompanying text-figure 26. 



Fig. 26. 



Fig. 26. Coccosteus decipiens Aga8siz. Lower Old Red Sandstone; Scotland. Lateral 

 aspect restored by Smith Woodward, in part alter Traquair. x i. TThe caudal fln is here 

 conjecturally represented as heterocercal, for which there is no evidence; it may be re- 

 garded with even greater probability as having been diphycercal.] 



Coccosteus rnacromus Cope. 



1892. Coccosteus rnacromus E. D. Cope, Proc. Amer. Phil. Soc. 30, p. 225. 

 1907. Coccosteus rnacromus C. R. Eastman, Mem. N. Y. State Mus. 10, p. 116. 



The only known examples of this species are those obtained 



by the late Professor Cope, whose original description is as 



follows : 



*Furbringer, K., Beitrage zur Morphologie des Skeletes der Dipnoer, etc. 

 Semon's Zool. Forsch. in Australien. Jena Denkschr. 1904, 4, p. 493. 



