460 THE POPULAR SCIENCE MONTHLY. 



shallows. Thus depth in the sea corresponded, in its effect upon dis- 

 tribution, to height on the hind. 



The same idea is applied to the explanation of a similar anomaly 

 in the Fauna of the iEgean : 



u In the deepest of the regions of depth of the JEgean, the representation 

 of a northern Fauna is maintained, partly by identical and partly by representa- 

 tive forms. . . . The presence of the latter is essentially due to the law (of rep- 

 resentation of parallels of latitude by zones of depth), while that of the former 

 species depended on their transmission from their parent seas during a former 

 epoch and subsequent isolation. That epoch was doubtless the newer Pliocene 

 or Glacial Era, when the Mya truncata and other northern forms now extinct 

 in the Mediterranean, and found fossil in the Sicilian tertiaries, ranged into that 

 sea. The changes which there destroyed the shallow-water glacial forms, did 

 not affect those living in the depths, and which still survive." ' 



The conception that the inhabitants of local depressions of the sea- 

 bottom might be a remnant of the ancient population of the area, 

 which had held their own in these deep fastnesses against an invading 

 Fauna, as Britons and Gaels have held out in Wales and in Scotland 

 against encroaching Teutons, thus broached by Forbes, received a 

 wider application than Forbes had dreamed of when the sounding ma- 

 chine first brought up specimens of the mud of the deep sea. As I 

 have pointed out elsewhere, 2 it at once became obvious that the cal- 

 careous, sticky mud of the Atlantic was made up, in the main, of shells 

 of Globigerina and other Foraminifera, identical with those of which 

 the true chalk is composed, and the identity extended even to the 

 presence of those singular bodies, the coccoliths and coccospheres, the 

 true nature of which is not yet made out. Here, then, were organisms, 

 as old as the Cretaceous epoch, still alive, and doing their work of 

 rock-making at the bottom of existing seas. What if Globigerina and 

 the coccoliths should not be the only survivors of a world passed away, 

 which are hidden beneath three miles of salt-water ? The letter which 

 Dr. Wyville Thomson wrote to Dr. Carpenter in May, 1868, out of 

 which all these expeditions have grown, shows that this query had be- 

 come a practical problem in Dr. Thomson's mind at that time ; and 

 the desirableness of solving the problem is put in the foreground of 

 his reasons for urging the government to undertake the work of ex- 

 ploration : 



" Two years ago, M. Sars, Swedish Government Inspector of Fisheries, had 

 an opportunity, in his official capacity, of dredging off the Loffoden Islands at a 

 depth of 300 fathoms. I visited Norway shortly after his return, and had an 

 opportunity of studying with his father, Prof. Sars, some of his results. Ani- 

 mal forms were abundant; many of them were new to science; and among 

 them was one of surpassing interest, the small crinoid, of which you have 

 a specimen, and which we at once recognized as a degraded type of the 



1 "Memoirs of the Geological Survey of Great Britain," voL L, p. 390. 

 3 " Lay Sermons," etc., " On a Piece of Chalk." 



