350 Mr. T. P. Barkas on Ctenoptychius. — 
PLATE XX, 
Fig. 1. Primitia simplex, var. Sanctojohannesiana, nov., outline of a right 
valve, magnified 23 diam. Cambrian; St. John’s, Newfound- 
land. a,side view; 6, end view. 
Fig. 2. Primitia simplex, var. Lloydiana, noy., outline of a complete cara- 
pace, magnified 23 diam. Cambrian; St. John’s, Newfound- 
land. a, side view, left valve shown; 0, end view; c, edge 
view. 
Fig. 3. Primitia simplex, var. Milneana, nov., right valve, magnified 
23 diam. Cambrian; St. John’s, Newfoundland. 
Fig. 4. Leperditia fabulites (Conrad), outline of a left valve, broken on 
the ventral margin, magnified 4 diam. Lower Silurian (?); 
Neile Bay. 
Fig. 6. Leperditia canadensis, Jones, left valve, broken, and showing 
another valve squeezed within it symmetrically, magnified 
4 diam. Lower Silurian (?); Neile Bay. 
Fug. 6. Leperditia Hicks, Jones, imperfect carapace, right valve shown, 
broken behind, magnified 4 diam. Menevian; St. David’s, 
South Wales. a, side view; 0, ventral outline of one valve. 
Fig. 7. Leperditia fabulites (Conrad), var. josephiana, Jones, right valve, 
in outline. Lower Silurian; St. Joseph’s Island, Canada. a, 
nat. size; 6,magn.2diam. —~ 
Fig. 8. Leperditia fabulites (Conrad), var. josephiana, Jones, perfect cara- 
pace, in outline, with left valve outwards, magnified 4 diam. 
Lower Silurian; Lebanon, Tennessee, U.S. a, side view; 8, 
hinder end; c, ventral edge. 
Fig. 9. Leperditia Billings, noy., internal cast of a carapace, not quite 
perfect at the dorsal corners, magnified 4 diam. Lower Silu- 
rian; near Lake Winnipeg. a, side view [right (?) valve seen | ; 
b, edge view. 
XX XIV.—Ctenoptychius or Kammplatten. 
By T. P. Barxas, F.G.S. 
To the Editors of the ‘ Annals.’ 
GENTLEMEN, 
Your correspondent Mr. Thomas Stock, of the Museum of 
Science and Art, Edinburgh, in his communication in your 
issue of August 1881, pp. 90-95, refers at some length to 
our present knowledge of the teeth of Ctenoptychius, and 
appears disposed to accept the theory of Professor Fritsch, 
that those specimens which I have named Ctenoptychius 
unilateralis are “‘ Kammplatten ” or “‘ Kammleisten,” belong- 
ing to Ophiderpeton, and associated with the anal orifice of 
that Coal-measure Labyrinthodont. 
The genus Ophiderpeton was established by Prof. Huxley 
on tolerably complete specimens obtaimed from Jarrow 
Colliery, Kilkenny, Ireland. The specimens were a few 
years ago in the natural-history work-rooms of the British 
Museum, and are now, I suppose, removed to the Kensington 
British-Museum Department. The matrices in which the 
