114 STUDIES IN LIFE AND SENSE. 



in the biography of the race. The rudimental shells of the two- 

 gilled cuttlefishes, like the teeth which never cut the gum in unborn 

 whales, have a reference not to their present life, but to a former state 

 of things. Contemplating the " pen " or " cuttle-bone " of a modern 

 squid or sepia, our thoughts become moulded in mental continuity 

 with the past. There rise to view before our mind's eye the ancient 

 nautili and their sculptured kith and kin the ammonites, crowding 

 the sea-beds of the far back Mesozoic, and still more remote Palaeozoic 

 ages. Then, through the operation of the inevitable laws of organic 

 progress and advance making the ancient world then, as they con- 

 stitute our world to-day, the theatre of continual change we see the 

 two-gilled stock arise in Secondary times from the four-gilled race. 

 First there is seen the modification of shell. Concurrently with the 

 decrease of shell comes increase of head-development and elaboration 

 of nerve-centres, tending to make the new two-gilled form what we 

 know it to be to-day the wary, watchful organism, living in the 

 waters above, and occupying a sphere of vital activity immeasurably 

 superior to the dull existence passed by its four-gilled ancestors on 

 the ocean bed. The shell degenerates more and more as the cuttle- 

 fish race rises on its own branch of the animal tree. Development 

 in numbers succeeds individual advance. The cephalopod tribes of 

 the present time dawn fuller and fuller as the Tertiary period progresses. 

 Thus the fulness of cuttlefish life to-day, exhibited in all its strange 

 weirdness, is interwoven, like the lines of human history itself, with the 

 warp and woof of the past. And not the least important clue to the 

 history of that past is found in the apparently insignificant " shell " 

 we have discussed ; since in its mere degeneracy, it leads us back- 

 wards in an instructive glance to those early times when the chief 

 branches on life's tree had not reached their full fruition, and to the 

 days when the world itself was young. 



