240 
SELACHfl. 
figs. 15 -17, from the Kinderhook Limestone, Iowa ; M. exsculptus , 
St. John & Worthen, tom. cit. p. 291, pi. y. fig. 18-22, from the same 
formation and locality ; and M. ornatus , St. John & Worthen, tom. 
cit. p. 294, pi. v. figs. 12-14, from the Upper Burlington Limestone, 
Illinois and Iowa. To Hybodopsis is assigned only one species, 
H. warcli , W. J. Barkas, tom. cit. p. 191 (with figs.), founded upon 
a fragm ent of ja w in the collection of Mr. John Ward, of Longton, 
from the Coal-Measures of Burnley, Lancashire. In the original 
description of the latter the calcified cartilage-granules are referred 
to as shagreen, the actual shagreen-granules being much larger, 
flattened and elongated, with more or less transversely-disposed 
wrinkles. 
Closely similar also are the Carboniferous teeth described under 
the names of Leioclus , St. John & Worthen 1 (Pal. Illinois, vol. vi. 
1875, p. 335), Desmiodus, St. John & Worthen (tom. cit. p. 337), 
and Chiastodus, Trautschold (Nouv. Mem. Soc. Imp. Nat. Moscou, 
vol. xiv. 1879, p. 58). 
To the first are assigned two species :— Leioclus calcar atus, St.John 
& Worthen, tom. cit. p. 336, pi. vii. figs. 11-18, from the Upper Bur¬ 
lington Limestone, Iowa and Illinois; and L. grossipunctatus , St. John 
& Worthen, tom. cit. p. 337, from the Iveokuk Limestone, Iowa and 
Illinois. Some of these teeth are uot much unlike a few Armagh 
specimens commonly referred to the so-called Helodus appencli- 
culatus , M‘Coy. 
Desmiodus comprises four species, as follow:— D. costelliferus, 
St. John & Worthen, tom. cit. p. 341, pi. x.A. figs. 10, 11, from the 
Upper St. Louis Limestone, Illinois and Missouri; D .(?) Jlabellum, 
St. John & Worthen, tom. cit. p. 343, pi. x. a. fig. 15, from the 
Upper Keokuk Limestone, Missouri; D. (?) ligonifonnis, St. John & 
Worthen, tom. cit. p. 342, pi. x.a. figs. 12-14, from the Upper 
Keokuk Limestone, Missouri aud Iowa; and D. tumidus, St. John 
& Worthen, tom. cit. p. 339, pi. x.a. figs. 7-9, from the Upper St. Louis 
Limestone, Illinois and Missouri. 
A single species is referred to Chiastodus , namely, C. obvcdlatus , 
Trautschold, tom. cit. p. 58, pi. vii. figs. 19-22. It is from the 
Carboniferous Limestone of Mjatschkowa, near Moscow. 
1 This name is preoccupied, Leiodon having been employed by Sir Richard 
Owen for a genus of Mosasaurian Reptiles (Odontogr. 1840-45, p. 261). 
