—=? 
%'c 6. C^r3, /43% , &*<. A/X- f. 6 
* ■ 4 .- 5 ^ *t 93 * h** > a- 
/=7 / ^ j,/. ,v.+*r* ' 
*-,/> 0 >£>G| * P ICHTHYODORULITES. 
^Atr»/iuk4| 
ft . 
—■ /*^A* 
,< I / 
129 
however, is unknown. Some of these fossils were originally named 
Oraccinthus obbreviatus, 0. fragilis , and 0. granulatus (J. S. New¬ 
berry, Bull. National Institute, 1857), but only the following two 
species have been fully defined :—• } A A4 * f . 
_ Accinthaspis armatus , J. S. Newberry, Rep. Geol. Surv. Ohio, 
£i^l vol. ii* pL b. (1875), p. 37, pi. lv. figs. l-Qy —Corniferous AA AA 
. "jA'r"” ,7 „ * Limestone (Lower Devonian) ; Ohio. [Columbia College, *'* 1 ?’ 3 
_C? f New York.] fifip 7 - 
Acantholejns pustulosus , J. S. Newberry, ibid. p. 38, pi. lvi. fiA 
/ figs. 1-6 h—Ibid. [Columbia College, New York.] V* 
.. ^ ,$■. ./O A jr*' ,u y* "• Tie L T(rw^ 
-- 1 * . >—■ / ^ S-JL. XV in' 
Genus STETHACANTHUS, Newberry. 
<2- 
[Palseoz. Pishes N. America (Mon. U. S. Geol. Surv. no. xvi. 
1889), p. 198.] 
Spines much laterally compressed, “ broadly falcate in outline, the 
conical summit compressed, with anterior and posterior margins 
rounded”; base of insertion broad. Convex margin with long 
sulcus exposing the internal cavity ; concave margin at about one- 
third of its length from the base “ rising into a strong, often tumid, 
shoulder”; sides unornamented, exhibiting the fibrous texture of 
the spine. 
This genus is not represented in the Collection, but the two 
following species are recognized:—■ 
C , /p. (Tdt-oCd ’ Tyl**-*4. 
XVcA 77oif\AS0in.oC, yTfd?- X*:*:/ X f/qfi. 
Stethacanthus altonensis , J. S. Newberry, Palaeoz. Pishes N. 
America (1889), p. 198, pi. xxiv.j: Physonemus altonensis , 
St. John & Worthen, Pal. Illinois, vol. vi. (1875), p. 454, 
pi. xix. figs. 1-3.—Upper St. Louis Limestone; Illinois 
and Iowa. [Type species.] 
Stethacanthus tumidus , J. S. Newberry, op. cit. p. 198, pi. xxv. 
figs. 1, 2.—Berea Grit; Berea, Ohio. [Columbia College, 
New York.] 
t'.S.tVaA At 
In texture and general aspect the spines thus described are so 
similar to those found with Gyracanthus , that it seems not impro¬ 
bable they may truly belong to an Elasmobranch already known by 
its fin-spines, which have received a distinct name. 
1 Both these descriptions and figures are reprinted in J. S. Newberry, 
Pakeoz. Fishes N. America (Mon. U.S. Geol. Surv. no. xvi. 1889), pp. 33-37, 
pi. xxxi. 
PART II. E 
