THE PAST AND PRESENT OF THE CUTTLEFISHES, in 



velopment of the four-gilled races which accords perfectly with the 

 theory of evolution and descent. The seas of the Trias, Oolite, and 

 Chalk periods must have literally swarmed with these striking forms 

 of cephalopod life ; but as the close of the Chalk period dawned, 

 and as the Secondary age came to an end, the fulness of the Am- 

 monite generations disappeared for ever. In the succeeding Tertiary 

 period not a single ammonite of any kind occurs ; the genus Nautilus 

 remaining in the Tertiary period as it survived into the Mesozoic 

 or middle period as the sole representative of a once plentiful four- 

 gilled population. 



If the history of the four-gilled cuttlefishes is thus plainly told as 

 having its beginnings in the Palaeozoic period, its maximum develop- 

 ment in the Mesozoic period, and its lingering presence in the Ter- 

 tiary period, the two-gilled cuttlefishes may be said to possess an 

 equally interesting history. Compared with their four-gilled neigh- 

 bours, the two-gilled forms are late-comers upon creation's scene. 

 Not a single fossil two-gilled form occurs in all the Palaeozoic 

 period extending from the Laurentian to the Permian rocks. If they 

 existed in Palaeozoic seas, they have at least left no trace of their 

 presence. Their softness of body may perchance have contributed 

 to their elimination from the oldest fossil records ; but laying aside 

 mere conjecture, we find the first fact of the past history of the two- 

 gilled forms in the presence of the fossil shells of the extinct Belem- 

 nites in the Triassic rocks. The Belemnites themselves disappear at 

 the close of the Mesozoic period ; but fossilised shells of species allied 

 to our living sepias occur in the Oolite ; and the internal shells of 

 squids are found in the Lias or lower Oolites. In the Tertiary rocks, 

 argonaut (fig. 9) shells occur in the Pliocene deposits ; the Eocene 

 rocks also give us sepia remains ; and various other two-gilled fossils 

 (Beloptera, &c.) are found in Eocene and Miocene formations. 



Briefly summarised, then, we find that the chief details in the past 

 history of the cuttlefishes are told when we are reminded that the 

 four-gilled forms are by far the more ancient of the two groups ; that 

 they first appear in the Silurian rocks, whilst the two-gilled forms 

 appear first in the Secondary rocks ; and, lastly, that the record of 

 the one group is the converse of the other. For, the four-gilled 

 species attained their maximum in the Primary and Secondary rocks, 

 and have practically died out, leaving the pearly nautilus as their sole 

 representative in existing seas. The two-gilled race, starting in the 

 Secondary rocks, and leaving the extinct belemnites as a legacy to 

 the past, have, on the other hand, flourished and progressed, and 

 attain their maximum, both in size and numbers, in the existing seas 

 and oceans of our globe. 



What ideas concerning the origin and evolution of these animals 

 may be legitimately deduced from the foregoing facts of their struc- 



