302 
ARTHRODIRA. 
Dinichthys ? precursor , J. S. Newberry, Palaeoz. Fishes N. America 
(1889), p. 51, pi. xli.—Corniferous Limestone (Lower 
Devonian) ; Sylvania, Ohio. [Median dorsal shield.] 
Dinichthys rinyuebcrgi , J. S. Newberry, op. cit. (1889), p. 60 : 
Dinichthys minor , E. N. S. Ringueberg (non Newberry), 
Amer. Journ. Sci. [3] vol. xxvii. (1884), p. 476, woodc. 
3. Portage Group (Lower Carboniferous); Stur¬ 
geon Point, New York. [Median dorsal shield.] 
7^r Newberry, Rep. Geol. Surv. Ohio, vol. i. 
\ v - t pk ii. (1873), p. 322, and ibid. vol. ii. pt. ii. (1875), p. 27. 
fb/.xxD‘‘. . °harts v., vi., and Palaeoz. Fishes N. America (1889), 
pi. iv. figs. 1, 2J: D. hertzeri , J. S. Newberry (, errore ), Rep. 
weol. Surv. Ohio, vol. i. pt. ii. pis. xxxii.—xxxiv.— 
Shale ; Lorain Co., Ohio. [Head, with jaws, &c. This is 
the largest known species, the transverse measurement of 
the occipital region of the cranium being 095.] 
(?) Dinichthys tuberculatus, J. S. Newberry, Trans. New York 
l —* Acad. Sci. vol. vii. (1888), p. 179, and op. cit. (1889), 
y, P* xxx ii. fig. 3.—Chemung Group (Upper Devo- 
^o. ^ ^ nian )» Warren, Pennsylvania, and Ohio. Also recorded 
-j* v . , from Psammite de Condroz, near Lie'ge, Belgium. [Por¬ 
tions of tuberculated plates.] 
''fay J*. . 
yenvs-vto-eArt,*- Genus TITANICHTHYS, 
.y*rs£-t/escndec/ JTrans. New York Acad. Sci. vol. v. 1885, p. 27.] 
xfcss- ^ es head and trunk [except plastron, which is unknown] 
leoiaer/t^. resembling those of Dinichthys , but relatively thinner. Mandibular 
rami without denticulations, long and slender, grooved in the ante¬ 
rior portion of the oral margin, as if for a horny sheath, and some¬ 
what turned upwards at the symphysis. 
ihe two known species of this genus attain a size even greater 
than those of Dinichthys , the cranium measuring not less than 1-25 
across the occipital region. They are described as follows, but are 
not represented in the Collection : — 
Titanichthys agassizi, J. S. Newberry, Trans. New York Acad. 
Sci. vol. v. (1885), p. 27, and Palaeoz. Fishes N. America 
(Mon. U. S. Geol. Surv. no. xvi. 1889), p. 133, pi. i. fi gs . 
1, 2, pi. ii. figs. 1, 2, pi. iv. fig. 4.—Cleveland Shale 
(Lower Carboniferous); Lorain Co., Ohio. [The type 
species. Head ; Mus. Comp. Zoology, Cambridge, Mass.] 
Titanichthys clarki, J. S. Newberry, Trans. New York Acad. Sci. 
vol. VI. (1887), p. 164, and Palaeoz. Fishes N. America 
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