90 PALAEONTOLOGY 



Of these forms, Ancyloceras alone is found in the oolites ; 

 all the rest are cretaceous ; and most abound in the alpine 

 districts of the south of France. 



Order 2. — DlBRANCIIIATA. 



( Cuttle-fishes.) 



Of the two great divisions of cephalopodous Mollusca, that 

 which is represented at the present day by the pearly Nautilus 

 was developed in the greatest profusion and variety in the 

 palaeozoic and secondary periods ; whilst the more active and 

 intelligent cuttle-fishes and squids have not been (certainly) 

 found in rocks older than the lias, and scarcely above 100 are 

 found in the whole secondary and tertiary series, while twice 

 as many have been obtained in existing seas. 



The Sejriadce are represented in the middle and upper 

 oolites by the genus Coccoteuthis (fig. 22, 6), whose strong and 

 granulated bone is furnished with broader lateral expansions 

 than the recent cuttle-fishes. In the older tertiaries of London 

 and Paris, many species of Sepia appear to have existed, but 

 only the solid mucro (fig. 22, 5) of the shell is usually pre- 

 served. In the miocene tertiary of Malta, a diminutive 

 cuttle-bone is not rare ; and at Turin a remarkable form 

 (S'piTidiTostra, fig. 22, 7) has been discovered, in which the 

 apex is provided with a chambered and siphonated cavity like 

 the shell of the Spirula. Two other genera, Bcloptcra (fig. 

 22, 8) and Bclemnoris, very imperfectly known by rare and 

 fragmentary examples, occur in the eocene tertiary. 



Remains of the Calamaries (Tcuthidai) are often found in 

 the fine-grained and laminated argillaceous limestones of the 

 lias and Oxford clays, as at Lyme Eegis, and Boll of Solenhofen. 

 Some of these are slender, like the pens of the recent Omma- 

 strephes, and furnished with a small conical appendix, as in that 

 genus ; whilst others are broad, and pointed at each end 

 (Beloteuthis). The most common form lias the shaft wide 



