xxii PROOFS, ILLUSTRATIONS, AUTHORITIES, ETC. 



Spirula. The observations of Peron and Lamarck having proved 

 that the animal of the Spirula possesses eight short arms and two 

 long tentacles, all provided with acetabula like the sepia, we regard 

 it as the type of the first family of the Decapoclous tribe, or that 

 which immediately succeeds the Tetrabranchiata." Cyclop, of 

 Physiology, Art. Cephalopoda. 



In short, and in plainer terms, Professor Owen has placed the 

 Decapodous tribe lowest, next the Tetrabranchiates, arid the Spirula 

 as the lowest of its tribe. 



And how is it that the Dibranchiates commence in the series of 

 formations p It is with the Belemnites, allied to the Spirula, the 

 type nearest the Tetrabranchiates. These appear in the Lias, and 

 their family "appear to be the sole representatives of the Dibran- 

 chiate Cephalopods throughout the whole of the Secondary Epoch." 

 Edwards, With the conclusion of that epoch perish all the sur- 

 vivors of the Tetrabranchiata, excepting only the Nautili, which 

 continue to the present time. 



During the tertiary epoch, the Cephalopoda are as remarkable for 

 their rarity as they were formerly for their abundance. Two genera 

 belonging to the family of Belemnitidse occur in the beds of the 

 Paris basin and in the Eocene formation of England. There are 

 also two species of Argonaut from the new tertiary formations on 

 the continent. This is the first appearance of the Octopoda, the 

 highest tribe, on the field of life. 



Fishes. " It is no argument against the views that naturally 

 arise out of the summary of the facts of Paleontology as they are 

 now known, to urge that ' the fish and reptiles of the secondary 

 rocks are as fully developed in their organization as those now 

 living.' (Sir Charles Lyell.} . . . One of the leading dis- 

 tinctions amongst animals is the position of the skeleton ; the great 

 binary division of Lamarck into vertebrata and invertebrata was 

 based upon this distinction ; and Cuvier's supplementary labours, 

 which made us better acquainted with the real nature and value of 

 the invertebrate groups, have served in the main to confirm the 

 reality of the great characteristic manifested in the internal or ex- 

 ternal position of the skeleton. 



" We have already adverted to the fact, that no completely ossified 

 vertebra of a fish had been discovered in the strata of the Silurian 

 and Devonian period. Those strata are of enormous extent, and 

 have been most extensively investigated. As regards the internal 

 skeleton, these primeval fishes were less fully developed than those 

 of the tertiary and existing seas. 



[Their external or dermal skeleton] was not only developed in ex- 

 cess, as compared with the great majority of recent fishes, but pre- 

 sented in its form and structure a closer analogy to the exo-skeletons 

 of invertebrata than that of any known fish which possesses the 

 same system of hard parts well calcified. In the Pterichthys, 

 Pamphractus, and Coccosteus, e. g., of the Old Bed Sandstone 



