1893. ] NEW YORK ACADEMY OF SCIENCES. 119 
Of course we can not say that all the fossils mentioned may 
be referred to the same source, but in regard to the specimens 
from the Chemung there can hardly be any doubt, and as all or 
nearly all the others are likewise from rocks representing geo- 
logical horizons in which sharks were plentiful, we may at least 
assume the probability of a similar origin for all. The matter, 
however, was only called to my attention two days ago, so that 
there has been no opportunity for anything like careful research, 
and we must leave any extended dissertation upon the subject 
until some future time, merely placing the fact of the compari- 
son upon record. 
EXPLANATION OF FIGURES. 
Fie. I. Cladoselache fylert, Newb. <A restoration drawn to scale ac- 
cording to measurements of type specimens (g¢+). The number of gill 
clefts, of which seven are figured, is here at the best approximate. 
Eight or nine may well have been present. The horizontal keel at the 
base of the caudal is represented by shading. The dorsal (?) fin is not 
definitely known. 
Fic. Il. C. fylert, Newb. Ventral aspect. The condition of the gill 
clefts ventrally has not been determined ; there is reason to believe that 
the anterior isthmus-flap was considerably larger than here indicated, 
and like that of the recent Chlamydoselache, may have extended caudad 
so as to protect the hinder clefts. The body width, if allowance be made 
for distortion in fossilization, is perhaps more accurately expressed by 
the maginal dotted lines. In ventral aspect the horizontal caudal keel 
is indicated by shading. 
Fic. Il. C. newberryi, nu. s. Ventral aspect. The right pectoral fin, 
together with outlines of ventrals, has beenadded. The left niandibular 
ramus and the hinder margin of the isthmus-flap are visible in the fossil. 
(xz). 
A. Coprolite (cf. Fig. VII.). 
B. Basalia of left ventral (cf. Fig. V.). 
C. Myomeres (cf. Fig. VI.). 
Fie. IV. C. newberryi. Pectoral fin (x1). Radialia straighter and 
ore compressed antero-posteriorally than in fyleri: fin’s body-length 
shorter. : 
Fie. V. C. newberryi. Basalia of ventral fin. These, although poorly 
preserved in the present specimen, agree in position with similar struc- 
tures in fyleri. 
Fie. VI. C. newberryi. Myomeres (x1). 
Fie. VII. C. newberryi. Coprolite (x1) showing well marked im- 
pression of spiral valve. 
Fie. VIL. C. newberryi. Circum-orbital derm plates (x1). 
Professor J. F. Kemp exhibited a series of thin sections of 
typical rocks by the lantern with polarized light. 
