54 
SELACHIX, 
vol. ii. (1866), p. 72, pi. iv. fig. 18; Peripristis semicircu- 
laris, 0. St. John, Final Rep. U. S. Geol. Surv. Nebraska, 
1872, p. 242, pi. iii. figs. 3, 4, pi. iv. fig. 20 ; Ctenoptychius 
semicircular is, J. S. Newberry, Rep. Geol. Surv. Ohio, vol. ii. 
pt. ii. (1875), p. 52, ph lviii. fig, 14.—Coal-Measures; 
Indiana, Ohio, Nebraska. "TCn v- . 
Ctenopty chius stevensoni, St. John & Worthen, tom. cit. p. 383, 
pi. xii. fig. 15.—Coal-Measures ; West Virginia. 
Ctenojptychius tripartitus : Petalodopsis tripartitus , J. W. Davis, 
Trans. Roy. Dublin Soc. [2] vol. i. (1883), p. 499, pi. Ik. 
fig. 6 ; and Quart. Journ. Geol. Soc. vol. xl. (1884), pi. xxvi. 
fig. 16. —U. Carboniferous Limestone ; Wensleydale, York¬ 
shire. 
Ctenoptychius vinosus : Ctenopetalus vinosus, St. John & Worthen, 
tom. cit. p. 396, pi. xii. fig. 13.—Keokuk Limestone; 
Iowa. 
An indeterminable ichthyolite, from the Scotch Old Red Sand- 
stone, has been described as Ctenopty chius priscus by Agassiz, Poiss. 
Foss. Y. Gres Rouge, 1844, p. 124. An unsatisfactory fossil, from 
the Rhaetic Beds of Aust Cliff, near Bristol, also appears to form the 
type of Ctenoptychius ordii , J. W. Davis, Quart. Journ, Geol. Soc. 
vol. xxxvii. (1881), p. 422, pi. xxii. fig. 8. 
A form of tooth, from the Northumbrian Coal-Measures, very 
suggestive of Ctenopty chius, was described under the name of 
Petalodopsis mirabilis by W. J. Barkas, Monthly Rev. Dental Surgery, 
vol. ii. (1874), p. 538, figs, xxx.-xxxii., and vol. iii. p. 4, figs, xxxiii.- 
xxxv. More recent researches, however, have shown that this is 
probably the vomerine tooth of Ctenoclus h 
Genus CALLOPRISTODUS, Traquair. 
[Geol. Mag. [3] vol. v. 1888, p. 85.] 
Syn, Ctenoptychius, L. Agassiz (in part.). 
Teeth with low crown, coarsely denticulated, having no folds at 
its base-line, which is straight both in front and behind. Root very 
long, fibrous, often divided below into a number of small irregular 
“ rootlets.” 
W. J. Barkas 2 has pointed out that the microscopical structure of 
the type species of this genus, C. pectrnatus, is very different from 
1 See W. J. Barkas, Proc. Roy. Soc. Yew South Wales, vol. x. (1876), p. 115, 
figs, xiv.-xix. Also T. Atthey. Ann. & Mag. Nat. Hist. [4] vol. xv. (1875), p. 310, 
pi. xix. fig. 4. 
2 Monthly Rev. Dental Surgery, vol. ii. (1874), pp. 482, 538, 
