SAUROID FISHES. 273 
Saiiroid Fishes in the Order Ganoid, 
The voracious family of Sauroid, or Lizard- 
like Fishes, first claims our attention, and is 
highly important in the physiological considera- 
tion of the history of Fishes, as it combines in 
the structure both of the bones, and some of the 
soft parts, characters which are common to the 
class of reptiles. M. Agassiz has already ascer- 
zerland, has long been one of the most celebrated, and least 
understood localities of fossil Fishes in Europe, and the mineral 
character of this slate had till lately'caused it to be referred to the 
early period of the Transition series. M. Agassiz has found that 
among its numerous fishes, there is not one belonging to a 
single genus, that occurs in any formation older than the Creta- 
ceous series ; but that many of them agree with fossil species 
found in Bohemia, in the lower Cretaceous formation, or Planer 
kalk ; hence he infers that the Glaris slate is an altered condition 
of an argillaceous deposit, subordinate to the great Cretaceous 
formations of other parts of Europe, probably of the Gault. 
Another example of the value of Ichthyology, in illustration 
of Geology, occurs in the fact, that as the fossil Fishes of the 
Wealden estuary formation are referrible to genera that charac- 
terize the strata of the Oolitic series, the Wealden deposits are 
hereby connected with the Oolitic period that preceded their com- 
mencement, and are separated from the Cretaceous formations 
that followed their termination. A change in the condition of 
the higher orders of the inhabitants of the waters seems to have 
accompanied the changes that occurred in the genera and species 
of inferior animals at the commencement of the Cretaceous for- 
mations. 
A third example occurs, in the fact that M, Agassiz has, by 
resemblances in the character of their fossil Fishes, identified the 
hitherto unknown periods of the freshwater deposits of Oeningen, 
and of Aix in Provence, with that of the Molasse of Switzerland* 
GEOL. T 
