306 
ELEMENTS OF GEOLOGY. 
Gryphma {JExogyra)^ Pecten^ Pkigiostoma {Lima)^ Trigonia^ 
Catill'us {Inoceramus)^ and TerebratiilaJ^ But Ammonites, 
as M. d’Archiac observes, of which so many species are met 
Avith in the chalk of the north of France, are scarcely ever 
found in the southern region; while the genera Hamite^ 
Turrilite^ and ScapMte^ and perhaps Belemnite^ are entirely 
wanting. 
On the other hand, certain forms are common in the south 
which are rare or wholly unknown in the north of France. 
Among these may be mentioned many Hippurites^ Sphmru- 
lites^ and other menabers of that great family of mollusca 
called Budistes by Lamarck, to which nothing analogous has 
been discovered in the living creation, but Avhich is quite 
characteristic of rocks 
of the Cretaceous era 
in the south of France, 
Fig. 2T6. 
Spain, Sicily, Greece, 
other countries 
bordering the Mediter- 
ranean. The species 
called PRppurites or- 
ganisans (Fig. 276) is 
more abundant than 
any other in the south 
of Europe; and the 
geologist should make 
himself well acquaint¬ 
ed with the cast of the 
/ interior, 6?, which is oft¬ 
en the only part pre¬ 
served in many com¬ 
pact marbles of the 
Upper Cretaceous pe¬ 
riod, The fiutings on 
riod. The fiutings on 
tain a great size and 
length, are wholly unlike the markings on the exterior of 
the shell. 
* D’Archiac, Sur la Form. Cretacee du S.-O. de la France, Mem. de la 
Sop. Geol. de France, tom. ii. 
t D’Orbigny’s Paleontologie fran 9 aise, pi. 533. 
