108 HAY—VERTEBRATES OF CARBONIFEROUS AGE. [March 16, 
of nearly square cells run out in all directions from the centre. I 
have seen no specimens except those described by Prof. Cope (U. S. 
Nat. Mus. Cat. Nos. 4372, 4394). 
SAGENODUS LACOVIANUS Cope. 
Sagenodus lacovianus Cope, E. D., Proc. AMER. PHILOs. Soc., 
XXXVI, 1997, p-. 79, El. i, Fig. 55> Williston, 5. W., Aways 
Univ. Quart., viii, 1899, p. 177. 
Sagenodus conchiolepis Cope, E. D., Proc. AMER. PHILos. Soc., 
AXXV1, 1697, D-. 79, b:.1, Pig: 4: 
Sagenodus conchiopsis (conchiolepis), Williston, S. W., Kansas 
Cniv. Quart., 1899, viii, p. 177. 
I regard as identical the two species which Prof. Cope has de- 
scribed and figured as above cited. In form the types differ in that 
S. lacovianus narrows somewhat toward the free margin and is 
more pointed, while S. conchiolepis is slightly wider posteriorly and 
is more truncated ; but nothing can be based on such differences. 
As regards the ornamentation, I find nodifferences. The type of S. 
conchiolepis is said to have the tessellated area continued to the edge 
of the scale, but this depends to a great extent on perfection of 
preservation, and with a good lens may be observed in places even 
in the type of S. /acovianus. Prof. Cope was mistaken, too, I 
think, when he said that in the type of .S. dacovianus there are no 
concentric lines except one coarse one. A number of others are 
present, but they require mostly the use of a lens. Prof. Cope 
stated that the sculpture of .S. conchiolepis, as in S. reticulatus, radi- 
ates from near the proximal end. ‘This I regard as an important 
character. An examination shows that in the types of both S. 
lacovianus and S. conchiolepis the centre of growth is at the ex- 
treme anterior end of the scale. In one of the specimens (U. S. 
Nat. Mus. Cat. No. 4391 = Cope’s F, 59, 60) which Prof. Cope 
has identified as S. refécudatus a considerable number of growth- 
lines may be seen sweeping around in front of the centre of growth ; 
so that, where the sculpture is well shown, this character may be 
employed to distinguish the scales. In the specimen of S. retecu- 
Jatus referred to, the centre of growth is removed from the anterior 
border of the scale one-fifth the whole length of the scale. In the 
U. S. Nat. Museum there is another scale (U. S. Nat. Mus. Cat. 
No. 4384), from the Lacoe collection made at Mazon creek, which 
is intermediate between the type of S. conchiolepis and that of S. 
