PEECOMOEPHI. 83 



the anal is below the penultimate dorsal ray. The caudal fin is openly 



forked. 



Measurements, 



M. 



Total length 061 



Length of head 016 



Length to line of ventral fin 020 



Length to line of dorsal fin 022 



Length to line of anal fin 031 



Length to base of caudal fin 048 



Depth at caudal peduncle 008 



Depth at dorsal spine Oil 



The more numerous rays of the dorsal fin, and more numerous scales 

 are among the characters which distinguish this species from the two above 

 described. It is dedicated to Dr. Frederick M. Endlich, geologist in 

 charge of one of the parties of the United States Geological Survey of the 

 Territories under Dr. F. V. Hayden. 



AMPHIPLAGA Cope. 



Bulletin U. 8. Geol. Surv. of the Terrs., 1877, p. 812 (August 15). 



Generally as in ErismaUypterus, but with strongly ctenoid scales. The 

 dorsal fin is over the abdomen, and is supported by a few strong, adherent 

 spines in front, which rest on stout interneurals; the soft rays have no inter- 

 neurals, either in this fin or the anal. They are present in Erismotopterus. 

 The ventrals originate a little in advance of the line of the dorsal, and the 

 caudal fin is deeply forked. This genus approximates Aphrodedirus. 



The scales in this genus are thin and like those of Trichophanes. In 

 other respects Amphiplaga resembles that type, and I have only distinguished 

 it on account of the absence of interneural bones below the soft dorsal 

 radii. It has occurred to me that this may be abnormal or due to accident, 

 but the bases of the dorsal radii, as well as the anterior interneural bones, 

 are perfectly preserved, so that the accidental removal of the posterior 

 interneurals seems improbable. It must also be remembered that the inter- 

 hsemal bones are absent from the soft anal rays in both this genus and in 

 Erismatopterus. 



But one species of this genus is yet known. 



