No. 394.] NAMES OF CERTAIN FOSSIL FISHES. 785 
script names, Xystrodus, to a species which had in 1855 been 
described and figured as Cochliodus striatus by McCoy. The 
name therefore must date from 1862. But in 1860 Plieninger! 
described with some minuteness some Hybodont teeth, to which 
he gave the name Aystrodus finitimus. This earlier use of 
Xystrodus makes it impossible, or at least unwise, to use it in 
the sense given it by Morris and Roberts. The name PLatyxy- 
STRODUS may be used instead. The type will be as before, P. 
striatus (McCoy). The American species are P. bellulus, P. 
imitatus, P. inconditus, P. simplex, and P. verus, all by St. John 
and Worthen. 
In 1883? Davis founded a genus of cochliodont sharks, to 
which he gave the name Tomodus. The name had, however, 
been used for other teeth in the same group by Trautschold in 
1879.° It was, therefore, clearly preoccupied. Subsequently 
Trautschold renamed his genus Oxytomodus, but this in no 
way made Tomodus more available for Davis’s genus. On this 
point see Mr. A. S. Woodward’s remarks. For the genus 
described by Davis, S. A. Miller® has proposed to substitute 
Icanodus. The type will, of course, be Z. convexus (Davis). 
One American species belongs doubtfully to the genus. This 
is Z. (?) léimitaris (St. John and Worthen). 
In 1843® H. von Meyer described, from the lower Miocene 
of Hesse Darmstadt, a species of ray which he called Mytiobatis 
serratus. Leidy," therefore, encroached on occupied territory 
when he named a fossil ray from the Eocene of New Jersey 
M. serratus. This may be called M. leidyi. 
Two species of fossil Dipnoi require new names. In 18778 
Professor Cope described remains which he denominated Cte- 
nodus gurleyanus. In 1889 S. A. Miller? modified the specific 
1 Neues Jahrb. Min., p. 695. 
2 Trans. Roy. Dublin Soc., [2], vol. i, p. 446. 
3 Nouv. Mém. Soc. Imp. Nat. Moscou, vol. xiv, p: 55. 
4 Cat. Foss. Fishes, vol. i, p. 191. 
5 N.A. Geol. Paleont., ist App., p. 716. 
6 Neues Jahrb. Min., p. 703- 
T Proc. Acad. Nat. Sci. Phila., p. 395. 
8 Proc. Amer. Philos. Soc., vol. xvii, p. 54. 
9 Pal@oz. Foss. N.A., P. 593- 
