NO. 2177. FOSSIL FISHES IN NATIONAL MUSEUM— EASTMAN. 261 



genus Sandalodus, solely on account of our lack of knowledge of the 

 anterior components of the complete dentition. The form of the 

 large crushing teeth of this species is unmistakably that of Deltodus, 

 as may be seen from an inspection of the example shown on plate 8, 

 fig. 3, which is from the St. Louis limestone near St. Louis, Missouri. 

 In geological range the species extends from the Burhngton to the 

 St. Louis limestone, inclusive. 



ICHTHYODORULITES. 



Under this head mention is made of certain interesting dermal 

 defenses of Carboniferous sharks which are preserved in the collection 

 and are worthy of special notice. The interpretation of some of 

 these structures as belonging to primitive Chimaeroids is a novel 

 feature. Generic names founded upon fin-spines and clasping organs 

 are to be understood as used in a provisional sense only. 



Genus CTENACANTHUS Agassiz. 



In the year 1902 descriptions were published by the present writer ^ 

 of several Kmderhook species of this genus, the types of which had 

 been acquired by the United States National Museum. At the time 

 of their description an exact record of the locality was imobtainable, 

 but at a later date the information was received from Prof. Charles 

 Schuchcrt that the types of C. longinodosus , C. lucasi, C. decussatus, 

 and C. solidus, together with the figured specimens of C. spectaUlis 

 and C. venustus, wore collected from the Kinderhook quarries at Le 

 Grand, in Marshall County, Iowa. The formation as exposed in tliis 

 vicinity is described m the Annual Report of the Iowa Geological 

 Survey, vol. 7, 1896, pp. 221-226. 



CTENACANTHUS GRACILLIMUS Newberry and Worthen. 



Plates, fig. 4; plate?, fig. 7. 

 Ctenacanthus gradllimus Newberry and Worthen, Pal. Illinois, vol. 2, 1866, 

 p. 126, pi. 13, fig. 3.— St. John and Worthen, Pal. Illinois, vol. 7, 1883, p. 

 238, pi. 24, fig. 1. 

 Acondylacanthus ocddentalis Newberry, Monogr. U. S. Geol. Siirv., vol. IG, 1889> 

 p. 206, pi. 25, fig. 6. 

 The reasons for miitmg the "species" described by Newberry and 

 Worthen as Peltacantlms (?) ocddentalis with C. gradllimus of the 

 same authors were pointed out by St. John and Worthen in 1883, 

 and reaffirmed by the present writer ui 1902.^ Under the designa- 

 tion of Acondylacanthus ocddentalis a distorted and worn spme from 

 the St. Louis limestone was figured by J. S. Newberry in 1889, evi- 

 dently through erroneous mterpretation. The specimen should prop- 

 erly be referred to the species now mider discussion, and a more per- 



1 Bull. Mus. Comp. Zool., vol. 39, No. 3. 



2 Idem., p. 86. 



