Ive 
Some Extinct Sharks and Ganoid Fishes.! 
UR conceptions of some of the more primitive groups of fishes 
have been greatly modified during the past few years. The 
discovery of nearly complete skeletons has shown that the frag- 
mentary fossils originally compared with the corresponding hard parts 
of existing animals truly belong to strange races of which no idea 
could be formed from their examination alone. Sharks, sturgeons, 
mud-fishes, and the fringe-finned ganoids, in Paleozoic times seem 
to have flourished under almost as many modifications as characterise 
the modern bony fishes in the fauna of to-day; and it becomes more 
and more evident, as discoveries continue, that the common ancestors 
of the class date back to a period hopelessly remote, so far as the 
palzontologist is concerned. 
Among those who have contributed an important share to the 
formation of these new conceptions, Dr. Anton Fritsch, of Prague, 
merits our special gratitude. He has for many years collected the 
fossil vertebrata from the Permian gas-coal formation of Bohemia, 
even preserving the pyritised specimens by removing the decayed 
bone and taking electrotypes of the impressions; and his great work 
descriptive of these fossils is the most painstaking and elaborately . 
illustrated monograph of its kind. Quite lately, a new instalment of 
the third volume has appeared, and the account of the fishes is now 
extended to include the Acanthodians and the first section of the 
Paleoniscids. 
Several years ago, in an earlier section of his work, Dr. Fritsch 
published the first detailed description of the singular primitive 
sharks known as the Ichthyotomi, supplementing the beautiful figures 
and brief notes of M. Charles Brongniart in his monograph on similar 
fossils from the French Coal-measures. Now, he adds further to 
our knowledge of the sharks by a detailed chapter on the Acan- 
thodians ; though in this case, unfortunately, he is able to contribute 
comparatively few new facts of fundamental importance, merely 
confirming, revising, and systematising the observations of previous 
authors. 
1 FAUNA DER GASKOHLE UND DER KALKSTEINE DER PERM-FORMATION BOHMENS. 
Vol. iti., pt. 2. By Professor Anton Fritsch. Prague: F. Rivnac, 1893. 
2E 2 
