410 PALEONTOLOGY OF OHIO. 



The characters relied on as indicative of the reference of Peplorhina to 

 the fishes are (1) the presence of opercula like those of Conchiopsis; (2) 

 the presence of jugular bones ; (3) of oval imbricated scales; and (4) the 

 absence of ambulatory limbs. The thin scutiform cranial bones, the 

 dense patch of vomerine teeth, and the mucous ducts of the bones and 

 scales are all ichthyic characters. As no limbs have been discovered in 

 three specimens preserved in the appropriate regions, their nature, if 

 existing, can not be determined at present. 



Peplorhina antheacina, Cope. 



L. c, p. 343. Conchiopsis exanthematicus, Cope; Loc. cit, p. 342. 



Represented by a cranium entirely preserved as to its outline, with 

 adjacent portion of space for chorda dorsalis and osseous ribs. The head 

 is covered with thin scuta, which are very faintly sculptured with a few 

 raised lines. The gular shields are oval and sculptured with elevated 

 points, producing a weakly rugose surface. The teeth above described 

 are on this fish. There are six in 3 mm. 



Width at shields, .055 m.; width at middle muzzle, .030; length of 

 head, .045. 



Scales large, well imbricated, covered with minute tubercles, which 

 form a rugose sculpture; each one is .01 m. in elevation, and three enter 

 .02 longitudinally. The gular scuta and opercula are smooth, except a 

 band of shallow grooves round the margin. 



Length of gular scutum, .021 m. ; length of scute behind it, .014. 



Ctenodus, Agass. 



But one specimen representing this genus has been found at Linton, a 

 remarkable circumstance when taken in connection with its abundance 

 in other coal fields where fossil Batrachians occur. 



Ctenodus Ohiensis, Cope. 



Proceedings Acad. Nat. Sci., Philad., 1874, p. 91. 



The type consists of a mould of the scuta of the upper surface of the 

 cranium. The top of the head is covered with angular plates or scuta 

 arranged in the following manner on the region preserved : Two sym- 

 metrical scuta occupy the median line, one in front of the other. One 

 of these is a longish or coffin-shaped hexagonal, with the suture with 



