110 PALEONTOLOGY. 



extremely light, slightly flexible, and elastic, but calcareous, 

 symmetrical shell, which is simple, and not divided into 

 chambers ; the vacated portion communicating with the rest, 

 and being used by the inhabitant as the receptacle for the 

 eggs. No authentic fossil homologue of such a shell has yet 

 been discovered. 



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 

 found in rocks older than the lias,* and the kinds, about 

 100, that, as yet, have been found in the whole secondary 

 and tertiary series are only about half as many as have been 

 obtained in existing seas. 



The Sepiadce are represented in the middle and upper 

 oolites by the genus Goccoteuthis (fig. 34, 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. 34, 5) of the shell is 

 usually preserved. In the miocene tertiary of Malta, a 

 diminutive cuttle-bone is not rare ; and at Turin a remark- 

 able form (Spiruliroslra, fig. 34, 7) has been discovered, in 

 which the apex is provided with a chambered and siphonated 

 cavity like the shell of the Spirilla. Two other genera, 

 Beloptera (fig. 34, 8) and Belemnosis, very imperfectly known 

 by rare and fragmentary examples, occur in the eocene 

 tertiary. 



Eemains of the Calamaries (Teuthidw) are often found in 

 the fine-grained and laminated argillaceous limestones of the 

 lias, as at Lyme Eegis, and of the upper oolites, as at Boll 



* The devonian Palceoteuthis ox Archceoteuthis of Ferd. Eoemer was founded 

 on a bone of Pteraspis. (See Woodward's Manual, p. 417.) 



