48 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



presented by the former genus are so well marked and distinctive 

 that there is seldom any difficulty in determining even the most 

 fragmentary individuals. The most obvious peculiarity of the 

 genus consists, as the name implies, in the remote position of 

 the dorsal fin. In Semionotus the dorsal is always anterior to 

 the anal fin, in Catopterus it is either opposite or posterior. The 

 margins of all the fins are closely set with fine fulcra, in such 

 wise that they present a delicately fringed appearance, and the 

 fin-rays themselves are very numerous, finely articulated, and 

 enameled. Other noticeable differences consist in the orna- 

 mented condition of the cranial bones, and serration of the hinder 

 margin of the scales. 



Whereas the genus Semionotus is represented in this country 

 by half a dozen or more species, its associates Catopterus and 

 Dictyopyge comprise a much smaller number, in fact not more 

 than one or two each. After a critical study of differential 

 characters we are forced to admit that only two species of Catop- 

 terus are capable of being clearly distinguished. These are 

 C. gracilis Redfield and C. redfieldi Egerton, both founded on 

 large and nearly complete fishes which differ from one another 

 chiefly as regards proportions of body and scale characters. The 

 so-called C. parvulus Redfield is probably to be regarded as the 

 young of C. gracilis, and the species named by Newberry C. minor 

 and C. ornatus are supposed to stand in a similar relation to 

 C. redfieldi. 



Catopterus gracilis J. H. Redfield. 



(Plates IX-XI.) 

 1837. Catopterus gracilis J. H. Redfield, Ann. Lyceum Nat. 



Hist. N. Y., iv, p. 37, pi. 1. 

 1 841. Catopterus gracilis W. C. Redfield, Am. Journ. Sci., 



[1] xli, p. 27. 

 1841. Catopterus gracilis E. Hitchcock, Final Rept. Geol. 



Mass., ii, pp. 44°, 460. 

 1888. Catopterus gracilis J. S. Newberry, Monogr. U. S. 



Geol. Surv., xiv, p. 55, pi. 16, figs. 1-3. 

 1895. Catopterus gracilis A. S. Woodward, Cat. Foss. 



Fishes Brit. Mus., iii, p. 2. 

 1905. Catopterus gracilis C. R. Eastman, Ann. Rept. N. J. 



Geol. Surv. for 1904, p. 96. 



