262 G. F. Eaton — Collection of Triassic Fishes at Yale. 



New Jersey, by W. C. Pedfield,* who at the same time gave 

 the name P. macropterus to specimens from these localities. 

 It appears that there was some doubt as to the validity of the 

 latter species, for, in 1848, a paper by J. H. Reol/ield was read 

 before the Association of American Geologists and Naturalists, 

 in which I. fultus and I. macropterus were discussed and were 

 united under the name I. fultus. The late Prof. Newberry, 

 belonging to a school of paleontologists whose practice it was 

 to decide all doubtful cases in favor of new species, again 

 separated the two forms ; and finally Dr. Woodward (loc. cit.) 

 reunited I. macropterus with /. fultus, and placed the latter 

 in the genus Semionotus, where it will doubtless remain, for 

 no generic difference has been shown between the American 

 Ischypterus and the Old World Semionotus established by 

 Agassiz in 1832. 



The only character of Semionotus macropterus, as described 

 by Prof. Newberry, that separates it from S. fultus is its 

 relatively greater depthf of body. Even this the author did 

 not state with much assurance, for after discussing the two 

 species at length without contrasting them, he used the follow- 

 ing words : " In most cases, however, there need be no doubt, 

 the fusiform and slender fish standing for I.fultus, the broader 

 one for I. macropterus." A careful examination of Prof. 

 Newberry's original collection at Columbia University shows 

 that, while one of the specimens (not a type) of I. macropterus, 

 in its pressed and flattened condition, is deeper than a type of 

 I.fultus, all the others are proportionately more slender. For 

 this reason Dr. Woodward's decision will be adopted, and the 

 specimens in the Yale Museum which have hitherto been 

 labeled I. fultus and I. macropterus will now be exhibited 

 under the name Semionotus fultus. The following descrip- 

 tion, while not as clear as could be desired, is as detailed as the 

 condition of the fossils permits ; and it will serve, at least, to 

 distinguish good examples of S. fultus from well-preserved 

 specimens of the other species : 



S. fultus, attaining a length of 9 inches and a depth of 2^ 

 inches. Origin of dorsal fin at mid-length. 



Origin of anal fin under middle of dorsal fin or somewhat 

 further to the rear, and on the third oblique scale-row in 

 advance of the dorsal fin. 



Origin of ventral fins slightly nearer to anal fin than to 

 pectoral fins. 



Dorsal fin fulcra about 12, rays about 10 (Plate Y, fig. 1). 



Anal fin fulcra about 12, rays about 10. 



Dorsal and anal fin fulcra long. Apparently 4 dorsal fulcra 



* This Journal, 1841. 



f Termed " broader " by Newberry. 



