TRIASSIC FISHES FROM SPITZBERGEN 
197 
Gegenbaur in his work «Vergleichende Anatomie der Wirbeltiere» (1898, p.567—571) 
has adopted the interpretation given by v. Rautenfeld for the skeleton of the ventral 
fins of the sturgeons, though he still continues to hold fast to his archipterygium 
theory. With regard to the pelvis in Polypterus he naturally follows, under these circum¬ 
stances, v. Dayidoff’s view, i. e. he takes it to be rudimentary. He explains the loss of the 
pelvis in Ganoids an Teleosts as due to an alteration in the function of the ventral fins. «Sie 
(the ventral fin) hat», he says, «bei den Ganoiden den bei Selachiern so machtigen Apparat 
des Mixipterygiums verloren, jedenfalls nicht ausgebildet, und damit schwand auch der 
Flossenstamm, und nur die Radien des Flossenskeletts erhielten sich. Das Schwinden des 
Stammes erklart auch den Verlust des Beckens, an welches er gestiitzt war.» 
Braus (1901, pp. 251—252) in connection with his extensive investigation of the 
paired fins in Ceratodus also entered upon the question of the skeleton of the ventral 
fins in fishes in general. According to his view both in sturgeons and higher Ganoids 
and Teleosts the pelvis and all the basals were completely reduced and replaced by 
new formations, which would have arisen by the fusion of proximal parts of the endo- 
skeletal radials. These now formations would be homologous with the middle segments 
in the endoskeletal radials of the Elasmobranchs. The radials that had then taken part 
in this new formation of basal elements would only be those that had originally been 
situated in front of the basale metapterygii; the others would be quite reduced. 
The view that the pelvis in Ganoids and Teleosts had been reduced has been 
opposed by Goodrich (1902; 1909, pp. 276—277) especially among other writers; in this 
he supports his opinions chiefly by facts from the fossil forms. He believes he can show 
a pelvis in primitive fossil Crossopterygii and also believes it probable that the so-called 
basal of primitive fossil Elasmobranchs corresponds to one. Starting from this he comes 
to the conclusion that the pelvis is a very old element, which ought to have existed 
even in the ancestors of the Teleosts and Elasmobranchs. He enters further on the 
difficulties that arise when one tries to explain the processes that would have lead to 
the reduction of the pelvis. In the main he tries to prove that so far no decisive proofs 
have been put forward to compel us to take the pelvic-like element in the recent 
Ganoid and Teleosts as being anything but a formation homologous to the pelvis of 
the Elasmobranchs, fossil Crossopterygians and Dipnoans. 
A view similar to that of Goodrich’s was arrived at later on by Derjugin and 
Rozhdestvensky on the basis of embryological investigations inTeleosts (1912, pp. 645—647). 
The brief survey I have given shows how little agreement there has been and there 
still is with regard to te interpretation of the different elements in the endoskeleton of 
the ventral fins in the recent Brachiopterygii (Polypterids cf. p. 147 above) and Actino- 
pterygii. It is true that after what has been seen from Derjugin’s and Rozhdestvensky’s (1912) 
exposition we may hope that a careful study of the ontogenetic development of the 
ventral fins may afford us a number of new views on the present problems, but one 
can scarcely expect to arrive at a solution 01 these problems merely from the evidence 
of recent fish fins. As in so many other cases we must wait to see what the primitive 
fossil forms have to tell us. 
In this connection I shall briefly give only certain of the views to which I hawe 
come myself. I do not intend to enter here on the arguments for these views but 
