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124 TRANSACTIONS OF THE [Fres. 23 
eum of Columbia College. This author finds, in fact, that 
the fins of ‘ Cladodus” afford no evidence as to lateral fold 
origin, asserts the presence of basal plates, and adduces the 
structure of the ventral fin to support his view as to the 
essentially modern character of the paired fins. The unique 
character of the body terminal as figured by Newberry, Jaekel 
regards as the restoration (in a graphite oil color) of the 
collector. While he emphasizes the modern structural charac- 
ters he notes, however, the phylogenetic importance of the 
circum orbital ring of derm plates (Acanthodian), 
At the present time discovery of new material by Rev, Wm. 
Kepler, of New London, Ohio, has enabled some of the 
structural characters of this interesting shark to be more 
critically examined. And in a paper, now in publication, the 
present writer has endeavored to consider the essential charac- 
ters in their relation, particularly, to the doctrine of lateral 
folds. 
It would appear in summary that this shark form (which the 
writer distinguishes from the Cladodus of Traquair, in which a 
monoserial archipterygium is present, by the new genus 
Cladoselache), presents the most manifest evidence as tothe lateral 
fold origin of the paired fins, The fins, as stated by Smith 
Woodward, are actual remnants of the derm fold. The 
unjointed rod-like radials proceed from body wall directly to 
the fin margin ; the fin surface, therefore, is as yet Jacking the 
specialization of the dermal margin and dermal rays. It would” 
now appear that the basal plates exist but in a most primitive 
condition ; their fusion into a plate is seen to occur to a partial 
degree in the pectoral fin, but the rotation outward of the 
posterior end of this trunk of basals does not as yet take place ; ~ 
the entire fin stem is still imbedded in thé body wall. In the 
ventral a most interesting condition occurs,—a more primitive 
arrangement would here very naturally be expected,—the 
basals in the body wall are as yet unfused, and are represented by 
rod-like bars of cartilage, which outwardly resemble basal joints 
belonging to the radials—and were, in fact, so interpreted by 
Jaekel. The proximal ends of the basals are in actual process 
of concentration near the anterior fin magin; the radials, 
however, are still more or less at right angles to the axis of the 
fish. Smith Woodward has already recorded one of the most 
significant features in the fin structure,—-the marked way in 
which the radials are crowded together side by side in the 
anterior fin margin,—giving rise, in fact, in the pectoral to the 
specialization of a ‘compact cut-water. The writer suggests that 
this tendency to compress the radial elements in the anterior 
