EASTMAN: CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 219 



species of Homacanthus vary considerably in curvature.^ The present form 

 may also be compared with the spines referred by Davis and Newberry to the 

 f;enus Hoplonchus, which is scarcely distinct from Homacantlius. Tlie single 

 American species assigned to Hoplonchus was originally described by New- 

 berry as Ctenacanthus parvulus, and occurs in the Cleveland Shale (Upper 

 Devonian) of Ohio. 



Formation ami Locality. — Chemung Group ; Warren, Pennsylvania. 



CTENACANTHUS Agassiz. 



In a recent number of this Bulletin (Vol. XXXIX., No. 3), several species of 

 Ctenacanthus were described from material belonging to the United States 

 National Museum, and derived from the Kiuderhook limestone of Ipwa. Some 

 of these spines had formed part of the Government display at the Omaha and 

 other expositions, previous to their coming to Cambridge, and when placed in 

 the hands of the writer for description the authorities at Washington were 

 unable to furnish a record of the exact locality whence they were obtained. 

 Since their description was published, however, information has been received 

 from Mr. Charles Schuchert, who ])urchased the specimens, that the types of 

 C. longinodosus, C. lucasi, 0. decussatus, and C. solidus, together with tlie figured 

 specimens of G. sjjectabilis and C. veimstus, were collected by a Mr. McCabe 

 from the Kinderhook quarries at Le Grand, near Marshalltown, in Marshall 

 County, Iowa. A description of the formation as exposed in this vicinity will 

 be found in Volume VII., pp. 221-226, of the Iowa Geological Survey Annual 

 Eeports (1896). 



FRAGMENTS OF DERMAL ARMOR AND OTHER UNIDENTIFIED 



REMAINS. 



Portions of calcified cartilage, detached tubercles, bosses, and tlermal plates 

 ai'e of not infrequent occurrence in nearly all members of the Mississippian 

 series, being particularly abundant in the Kinderhook and St. Louis lime- 

 stones ; and in a few instances nearly complete cartilaginous and osseous jaws 

 have been brought to light, some of them dentigerous. None of these frag- 

 mentary remains are capable of satisfactory determination, although the more 

 characteristic of them have received provisional designations, such as Petrodus, 

 Stemmatias (Stemmatodus St. J. and Worth. 7ion Heckel), Mazodus, etc. The 

 wide range of form and ornamentation displayed by these bodies is remarkable, 

 and it is evident that Carboniferous fishes possessed a much more varied ex- 

 ternal covering than their Devonian predecessors. 



The survival of moribund Arthrodires during at least a part of the Kinder- 

 hook is witnessed by occasional dermal plates displaying the structure and 

 tuberculation characteristic of this group. An examination of weathered and 



1 Trans. Roy. Dublin Soc. (2), Vol. I., p. 361, PI. XLVIII., Figs. 7-9. 



