88 PALEONTOLOGY. 



Strombidce. — The Strombs with their massive shells, never- 

 theless, resemble the fragile Nucleobranchs in some respects. 

 They have the same lingual dentition, and the same carni- 

 vorous habits ; and though living on the sea-bed, they rather 

 leap than glide, having a narrow sole and a deeply-divided 

 operculigerous lobe. Characteristic of the warmer zones of 

 existing seas, they are only found fossilized in the newer 

 tertiary strata of countries south of Britain ; but there is a 

 group of little shells related to the recent Strombus ftssurellus 

 in the older tertiaries of London, Paris, and America, to which 

 Agassiz has given the name Rimella. The allied genus of 

 scorpion-shells (Pterocerd), now peculiar to eastern seas, has 

 been described as occurring fossil in the secondary strata of 

 Europe ; but the extinct species appear to be more nearly 

 related to Aporrhais. This genus, now confined to the 

 western shores of Europe, occurs in all the tertiaries, and is 

 represented in the secondary rocks by many remarkable 

 forms. Some have been separated under the name Alaria, 

 and to this group the so-called Pterocera Bentleyi may perhaps 

 be referred (fig. 27, 2). Rostellaria and Seraphs (or Terebellum), 

 now peculiar to the Eed or eastern seas, are conspicuous 

 fossils of the European eocene, at which time their range 

 extended to America. Some of the ancient Eostellarias have 

 the outer lip enormously expanded, as in the R. ampla (Hip- 

 pocrena) of the London clay. In the oolites and chalk there 

 are slender fusiform shells (Spinigera, d'Orb., fig. 27, 1) with 

 spines on the sides of the whorls, as in some recent Ranellce. 



Muricidce. — The great" family of whelks, by far the most 

 important group of living sea-shells, is scarcely of higher 

 antiquity than the eocene tertiary. The Ptirpurina of the 

 oolites (fig. 27, 3), and Columbellina of the chalk, are extinct 

 genera somewhat resembling Purpura and Cohimbella. But 

 since the so-called " cones " of the oolites have proved to be 

 Tornaiellce, it may not be unreasonable to distrust these other 



