G. F. Eaton — Collection of Triassic Fishes at Yale. 261 



here some characters of the scales which have not been empha- 

 sized by previous writers. The most handsome and complete 

 specimens do not generally show the form of the overlapped 

 portions of the scales. Such details are occasionally to be 

 seen in the dissociated scales of fragmentary specimens. 

 Unfortunately the same conditions which make this possible 

 may also render the specific identification difficult and uncer- 

 tain. Slightly at variance with Dr. Woodward's statement in 

 regard to the scales,* " the narrow overlapped margin not pro- 

 duced at the angles," most of the American species show the 

 antero-superior angle of the lower flank scales produced to a 

 marked degree, and there is reason to suppose that this char- 

 acter holds good throughout the American division of the 

 genus. Hot only is the " peg-and-socket articulation " found 

 in the flank scales generally, the pegs extending upward from 

 the superior border of the scales, but the present writer has 

 prepared for the Yale Museum an example of Semionotus 

 from Boon ton, N. J., in which the lower flank scales of the 

 ventral region articulate by a second series of pegs and sockets 

 (Plate VI, ~B-g. 3). The anteroinferior angles of these scales 

 bear peg-like processes, similar in size and form to those of 

 the upper border, which lie under the posterior margins of the 

 adjacent scales. The specimen displaying this double articula- 

 tion is of uncertain specific identity, and it would be quite 

 useless, at present, to speculate upon the prevalence of this 

 character throughout the genus. 



Semionotus fultus Agassiz. 



Palceoniscus fultus L. Agassiz. 1833. Poiss. Foss., vol. ii, pt. i. 

 Palceoniscus fultus W. C. Eedfield. 1841, This Journal, vol. xli. 

 Palceoniscus macropterus W. C. Eedfield, 1841, ibid. 

 Ischypterus fultus Sir P. Egerton, 1847, Quart. Jour. Geol. Soc, vol. iii. 

 Ischypterus fultus J. S. Newberry, 1888, Mon. TJ. S. Geol. Surv., No. xiv. 

 Ischypterus macropterus J. S. Newberry, 1888, ibid. 



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

 Nat. Hist., pt. iii. 



A number of specimens seeming to Prof. Newberry to offer 

 slight differences in the proportions of length and depth were 

 arranged by him in two species — Ischypterus fultus and I. 

 macropterus. These specific names had been used previously, 

 their history being as follows: In 1833 Palceoniscus fultus 

 was given by Agassiz, in his Poissons Fossiles, to small and 

 imperfect specimens from Sunderland, Mass. The species was 

 afterwards placed in the new genus Ischypterus, by Sir Philip 

 Egerton. t Meanwhile, the name Palceoniscus fultus was 

 applied to specimens from Massachusetts, Connecticut, and 



*Loe. cit. f Quart. Jour. Geol. Soc, vol. iii, 1847. 



