98 LIFE ON THE EARTH. 



in the Palaeozoic Strata. If we place the Mesozoic 

 fossil shells, formerly called Rostellaria (now Alaria), 

 and Cerithium, in the holostomatous division as 

 Morris and Woodward dothere will remain but few 

 exceptions to the rule that the Palaeozoic and Meso- 

 zoic Gasteropoda belong to the herbivorous division. 

 Euomphalus and Murchisonia are Palaeozoic; Alaria 

 and Nerinsea, Mesozoic. The function of the Carnivora 

 was in the earliest of these periods principally exer- 

 cised by Cephalopoda ; in the later period Fishes and 

 Reptiles were effective as allies, or opponents. 



Cephalopoda, among the most abundant as well 

 as highest in organization of all the fossil mollusca, 

 are much less numerous in the modern than they 

 were in the older periods. If we class them by the 

 organs usually called arms or feet, as Octopod, Deca- 

 pod, and Polypod, we find no trace of the first in the 

 Strata of the British Isles, though Argonauta is fossil 

 in the Italian Tertiaries. Decapod fossil genera more 

 or less allied to the recent Loligo, which includes a 

 long horny pen ; to the recent Sepia, which contains a 

 broad calcareous plate, thickly fibrous in front, con- 

 cave behind, and ending in a solid apex ; and to the 

 fossil Belemnite, which is of a long conical figure, 

 concave and chambered in front, fibrous behind, and 

 sometimes mucronated. These are all absent from 

 the Palaeozoic Strata, and Belemnites, by far the 



