No. 430.] PAIRED LIMBS OF VERTEBRATES. 775 
record, or that by Silurian he means Devonian, an age in 
which, by the way, we must admit that Cladoselache occurs. 
He surely cannot refer in the above terms to the minute frag- 
ments of Ostracophores of Oesel, which were once, about a 
decade ago, referred to as ganoidean and dipnoan. 
And most recently Dr. Braus! has considered in a special 
paper the later discoveries in fin structures in fossil selachians, 
and has even concluded that “through paleontology the theory 
of Gegenbaur has been given new life." Braus, however, makes 
no reference in this connection to the archipterygial characters 
of unpaired fins, nor yet to acanthodians, and furthermore, he 
treats all extinct forms without reference to their different 
geological horizons. The pectoral fin of Cladoselache he regards 
as essentially similar to that of Chlamydoselachus, believing that 
its metapterygial region has been obscured by the overlying 
body wall during the process of fossilization, and that the fin in 
reality possessed a lobate base which projected from the body 
wall, as in the recent shark. He accordingly must believe that 
the continuous posterior dermal margin of the fin in the fossils, 
as several writers have figured it,? is not a just one. I think, 
however, that I am justified in stating that this reactionary 
view finds no support in any known? specimen of this form. 
And I may further add that the line which continues the web 
of the lappet-shaped fin along the side of the body, which 
Braus is skeptical about, and which is hostile to the Gegen- 
baurian theory, is preserved in faultless condition in as many as 
à dozen specimens which are now under my hands.  Braus 
further believes that the ventral fin of Cladoselache shows a 
trace of a distinct metapterygium (as of Chlamydoselachus), 
inasmuch as radials occur in the hinder portion of the fin web, 
1 Verhandlungen d. Phys.-Med. Gesellsch. zu Würzburg (N.F.), Bd. xxxiv (1901), 
PP- 177-192 ; cf. also Zool. Forschungsreisen, Bd. i (1901), Lieferung III, PP- 197, 
? The fin margin has thus been figured — rounding in along the body wall — 
undissentingly by at least four authors. Braus does not consider this important 
feature of the fin, which I am sure he would have felt bound to do had he 
examined actual specimens. 
*I speak confidently, since I have good reason to believe that all cladose- 
lachids have hitherto been obtained through three collectors in Ohio, whose out- 
Put I have had the opportunity of examining. 
