96 ANNUAL REPORT OF 



have a general Palseoniscid aspect, the eye being far forwards, 

 snout prominent, and gape of the mouth wide. In this short- 

 lived family, also, specialization had not advanced so far as to 

 result in the correlation of the dermal rays of the unpaired fins 

 with their endoskeletal supports, and the scales are all rhombic 

 and ganoid, as in the more ancient types. 



Remains of Catopterus are on the whole less abundant than 

 those of the accompanying genus Semionotus, both in New Eng- 

 land and New Jersey, and as a rule are less perfectly preserved. 

 Nevertheless, the characters presented by the former genus are 

 so well marked and distinctive that there is seldom any diffi- 

 culty 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, in Catopterus it is either 

 opposite or posterior. The margins of all the fins are thickly set 

 with fine fulcra, and present in consequence a delicately fringed 

 appearance, and the fin-rays themselves are very numerous, finely 

 articulated, and enameled. Other noticeable differences con- 

 sist in the ornamented condition of the cranial bones, and serra- 

 tion of the hinder margin of the scales. 



Although the genus Semionotus is represented in this country 

 by half a dozen or more species, only two of Catopterus can be 

 definitely recognized. These are C. gracilis Redfield and C. Ted- 

 Heidi Egerton, both founded on large and nearly complete fishes 

 which differ from one another chiefly in the proportions of body 

 proportions and scale characters. The so-called C. parvulus 

 Redfield is probably to be regarded as the young of C. gracilis. 

 Catopterus minor and C. ornatus Newberry are supposed to stand 

 in a similar relation to C. rediieldi. 



Catopterus gracilis J. H. Redfield. 



(Plate XIII.) 



1837. Catopterus gracillis, J. H. Redfield, Ann. Lyceum Nat. Hist., N. Y., vol. 



vol. iv., pp. 37-39, pl- i- 

 1841. Catopterus gracilis, W. C. Redfield, Amer. Journ. .Sci., vol. xli., p. 27. 

 Catopterus gracilis, J. S. Newberry, Monogr. U. S. Geol. Surv., vol. xiv., 

 p. 55, pl. xvi., Figs. 1-3. 



