G. F. Eaton — Collection of Triassic Fishes at Yale. 265 



incident is of especial interest in connection with the discussion 

 of I. Agassizii in Prof. Newberry's monograph, where he 

 writes " I have seen no such fishes as these anywhere except at 

 Boonton. * * * At Sunderland occurs another species (I. 

 31arshii) which in form and general aspect resembles those 

 under consideration, but it is narrower, with less strong dorsal 

 and anal fins, with thicker and relatively broader scales, which 

 form more oblique rows on the sides. For these reasons I have 

 thought it wise to regard it as distinct." 



So far as comparison can be made, the three fishes at the 

 American Museum of Natural History, labeled I. Agassizii, 

 agree with the type of S. Marshi in size and form of body, 

 size, form, and obliquity of scales, and relative position and 

 structure of fins. The specific description here offered is based 

 upon these specimens jointly with the type at Yale : 



Semionotus Marshi, attaining a length of 12 J inches and a 

 depth of 3|- inches. 



Relative position and size of fins about the same as in 

 S. fultus. 



Dorsal fin fulcra about 14, rays about 9. 



Anal fin fulcra about 14, rays about 9. 



Apparently 4 dorsal fin fulcra originate on the dorsal line 

 over basal supports, the 5th being nearly equal in length to 

 one-half the anterior margin of the fin. 



Pectoral fin fulcra about 14, rays about 12. 



Tentral fin fulcra about 12. 



The flank scales usually have the postero-inferior angles a 

 little less pointed than in S. fultus (Plate Y, figs. 5 and 12), 

 and have the antero-superior angles continued forward as distinct 

 processes under the overlapping scales (Plate Y, fig. 9 ; Plate 

 YI, fig. 2). The deepest scales are in the 3rd or 4th oblique 

 row behind the clavicular arch ; these are about twice as deep 

 as long. Scales near the lateral line under the dorsal fin are 

 equilateral. 



The maximum depth is midway between the pectoral and 

 ventral fins, where the oblique rows comprise about 19 scales. 

 Horizontal row along lateral line comprises about 34 scales. 



The last scale of the anterior dorsal ridge has its posterior 

 end produced into a fine point (Plate Y, fig. 10). 



Semionotus tenuiceps Agassiz. 



Eurynotus tenuiceps L. Agassiz, 1835, Poiss. Foss., vol. ii, pt. i. 

 Eurynotus tenuiceps J. H. Redfield, 1837, Ann. Lye. Nat. Hist. N. Y., vol. iv. 

 Palceoniscus lotus J. H. Eedfield, 1837, ibid. 



Ischypterus tenuiceps J. S. Newberry, 1888, Mon. U. S Geol. Surv., No. xiv. 

 Semionotus tenuiceps A. S. Woodward, 1895, Cat. Foss. Fish., British Mus. 

 Nat. Hist., pt. iii. 



This is one of the two American species of Semionotus ap- 

 proved by Dr. Woodward. Except in its young form it may be 



