THE STATE GEOLOGIST. 91 



the adult, and in the other with immature forms belonging- to 

 one and the same species. 



Little can be added to the definition already given of 5. line-* 

 atus } for the reason that no further satisfactory material has 

 come to light. In determining fragmentary individuals, the 

 chief features to be relied upon are first of all the dorsal and anal 

 fin-fulcra, which form a fringe fully as wide at the base as in 

 S. oz'atus, are as strongly curved as in that species, and are 

 relatively longer. The moderately deep trunk, conspicuous ribs, 

 and minor scale characters are also of service in distinguishing 

 these fishes from other members of the same fauna. 



Semionotus elegans (Newbeny). 



(Plate XII.) 



1888. Ischypterus elegans, modestiis, lenticularis, J. S. Newberry, Trans. N. 



Y. Acad. Sci., vol. vi., p. 127 (names only). 

 18S8. Ischypterus elegans, J. S. Newberry, Monogr. U. S. Geol, Surv., vol. 



xiv., p. 37, pi. vii., Fig. 2 ; pi. x., Fig. 1 ; xiv., Figs. 1,2. 

 1888. Ischypterus modestns, J. S. Newberry, ibid, p. 38, pi. ix., Figs. 1-3. 

 1888. Ischypterus lenticularis, J. S. Newberry, ibid, p. 39, pi. x., Figs. 2, 3. 



D. 11 ; C. 15 ; A. 7. Lat. line scales about 32 (fide Newberry). 



A species of slightly smaller size than the preceding, and. dis- 

 tinguished from it only by its fin and scale characters. Dorsal 

 fin arising at mid-length, with 12 fulcra, which are shorter and 

 more closely appressed than in ,S\ lineatus. Anal fin not extend- 

 ing to the base of the tail, with about 10 fulcra. Squamation 

 regular, firmly united, and hence usually preserved intact; num- 

 ber of scales along the lateral line about 32, in transverse rows 

 at widest part of trunk about 20; ridge-scales in advance of the 

 dorsal fin 18-20, moderate in size; the hindermost ridge-scale 

 shield-shaped, not emarginate posteriorly. Dorsal and ventral 

 outlines symmetrically arched, but rapidly contracting behind the 

 median fins to a depth equal only to about half that of the middle 

 of the trunk. 



It will be noticed in the above synonymy that three of New- 

 berry's species are united under one head. The propriety of this 

 arrangement is self-evident, there being absolutely no characters 



