374 Annals of the Carnegie Museum. 



have but one, a median tooth, which is the extremity of a long median 

 longitudinal carina. The species of section I are D. dentatus, D. 

 analis and D. pectorosus; those of section II are D. humilis and D. 

 altus."* 



It remained for President Jordan, thirty years later, to give validity 

 to the distinction just noticed by elevating Cope's " section II " of 

 the genus Diplomystus to the rank of an independent genus (or sub- 

 genus, as suggested in the Annals of the Carnegie Museum, Vol. 

 VII, 1910). This was named Knightia,* the species chosen for its 

 type being the previously described Clupea humilis of Leidy, afterward 

 renamed C. pusilla by Cope. Dr. Jordan substituted the new specific 

 title eocena for that bestowed upon the species by the original author, 

 the combinations of Clupea humilis and Clupea pusilla being pre- 

 occupied among recent fishes. In this connection it should be re- 

 marked that the name Diplomyste Bleeker (= Diplomystax Giinther, 

 and Diplomystes Dumeril) refers to an existing genus of South Amer- 

 ican Silurids, and is not to be confused with the term proposed by 

 Cope. Copeichthys of Dollo (Results Voyage Belgica, 1904, p. 159) 

 is a synonym of Diplomystus, the former name having been substituted 

 under an erroneous idea that. Cope's term was preoccupied. 



Other occurrences of Diplomystus in the fossil state are in the Upper 

 Cretaceous of the Lebanon, Istria, Dalmatia, and Brazil; in the Lower 

 Oligocene (Osborne beds) of the Isle of Wight; and in the supposed 

 late Cretaceous or early Tertiary fresh-water shales at Riacho Doce, 

 Brazil (two species described by Jordan as Ellipes branneri and E. 

 riacensis). 6 



Besides the above mentioned fossil forms, a recent Diplomystid 

 which has been described under the name of Clupea (Hyperlophus) 



4 Cope, E. D., A Contribution to Our Knowledge of the Ichthyological Fauna 

 of the Green River Shales, Bull. U. S. Geol. Survey Territ., Vol. Ill, 1877, p. 808. 



6 Univ. Cal. Publ., V, No. 7, p. 136, 1907. 



6 Regarding Ellipes Dr. Jordan remarks in the paper above cited: " In any event 

 I think that we are justified in recognizing Ellipes, Potamalosa, Hyperlophus and 

 Knightia as distinct subgenera, even if we should wish to place all double-armored 

 herrings in the single genus, Diplomystus " (I. c, p. 25). 



In Dr. Jordan's scheme Cope's species D. longicostatus , from the Upper Cre- 

 taceous of Bahia, Brazil, finds a place under the new generic or subgeneric caption 

 of Ellipes. It is doubtful, however, if the proposed separation can be maintained 

 in actual practice, as the majority of specimens fail to disclose the characters relied 

 upon for distinctive criteria. 



