240 
SELACHII. 
figs. 15-17, from tho Kinderliook Limestone, Iowa; M. exsculptns, 
St. John & Worthen, tom. oil. p. 291, pi. v. fig. 18-22, from the same 
formation and localit}' ; and M. ornatus, St. John & Worthen, tom. 
cit. j). 294, pi. V. figs. 12-14, from the Upper Burlington Limestone, 
Illinois and Iowa. To Hybodopsis is assigned only one species, 
II. wardi, W. J. Barkas, tom. cit, p. 191 (with figs.), founded upon 
a fragment of jaw in the collection of Mr. John Ward, of Longton, 
from tho Coal-ilcasures of Burnley, Lancashire. In the original 
description of the latter tho calcified cartilage-granules are referred 
to as shagreen, tho actual shagreen- granules being much larger, 
flattened and elongated, with more or less transversely-disposed 
wrinkles. 
Closely similar also are tho Carboniferous teeth described under 
the names of Leiodus, St. John & Worthen' (Pal. Illinois, vol. vi. 
1875, p. 335), Desmiodus, St. John & Worthen {tom. cit. p. 337), 
and Ohiastodus, Trautschold (Nouv. Mem. Soc. Imp. Nat. Moscou, 
vol. siv. 1879, p. 58). 
To the first are assigned two species : — Leiodus culcaratus, St. J ohn 
& Worthen, tom. cit. p. 33(5, pi. vii. figs. 11-18, from tho Upper Bur- 
lington Limestone, Iowa and Illinois; and L.yrossipunctatus, St. J ohn 
& Worthen, tom. cit. xj. 337, from the Keokuk Limestone, Iowa and 
Illinois. Some of these teeth are not much unlike a few Armagh 
8X)ceimens commonly referred to the so-called Uelodus appendi- 
culatus, M‘Coy. 
Desmiodus comprises four species, as follow : — D. costcllifems, 
St. John & Worthen, tom. cit. p. 341, pi. x.a. figs. 10, 11, from the 
UiJpor St. Louis Limestone, Illinois and Missouri; D.{?)JlaheUum, 
St. John & Worthen, tom. cit. p. 343, pi. x. a. fig. 15, from the 
Upper Keokuk Limestone, Missouri; D.{‘!) ligoniformis, St. John & 
Worthen, tom. cit. p. 342, pi. x.a. figs. 12-14, from the Upper 
Keokuk Limestone, Missouri and Iowa ; and D. tumidus, St. J ohn 
& Worthen, tom. cit. jj. 339, pi. x.a. figs. 7-9, from the Upx>or St. Louis 
Limestone, Illinois and Missouri. 
A single species is referred to Chiastodiis, namely, C. obvcdlatus, 
Trautschold, tom. cit. p. 58, pi. vii. figs. 19-22. It is from the 
Carboniferous Limestone of Mjatschkowa, near Moscow. 
' This name is preoccupied, Leiodon having been employed by Sir Eichard 
Oweji for a genus of Mosasaurian Eeptiles (Odontogr. 1840-45, p.201). 
