200 Prof. W. King on Oceanic Sediments^ and 



of the sarcode was carried on within its cliambers, a forami- 

 nifer-shell would be limited to tlic superficial stratum, rising 

 and sinking therein, as if it were animated and it preferred 

 darkness to light. Eventually, gas ceasing to be generated, 

 and the chambers becoming tilled with water, the shell sinks 

 to the bottom. 



These suggestions, it api)ears to me, are fully capable of 

 ex])laining not only the presence of foraminifer-shells in the 

 greatest abundance in the superficial stratum after sunset 

 (assuming that the observations made by Major Owen and 

 others are conclusive on this point*), but how it is that the 

 specimens taken in tlie tow-net are often fresh, trans])arcnt, 

 and occasionally furnished with spines in a wonderful state 

 of preservation t; while those obtained from the bottom are 

 usually in an opaque or chalky condition. On the view that 

 these organisms habitually live at the bottom, it may be 

 urged that some specimens in the living state ought to be 

 brought up by the dredge or sounding-apparatus. Consider- 

 able doubt, however, may be entertained as to such possessing 

 any vital power, considering the greatly altered conditions of 

 temperature and pressure they would be subject to during the 

 ascent ; and it is highly improbable that many of them would 

 retain their delicate spines. As the problem does not seem to 

 be difficult of solution, let us hope that it will not remain long 

 in its present unsettled state. 



As regards the nature of the various substances forming 

 the sea-bottoms, the general concurrence of the recorded ob- 

 servations goes far to prove that generally wherever the depth 

 increases beyond 2600 fathoms the foraminifer-ooze gives 

 place to argillaceous deposits, one kind marked " grey ooze " 

 and the other " red clay" in the ' Challenger's ' charts, — that, 

 instead of a substance convertible into limestone or chalk, 

 there occurs at depths approaching and exceeding 3000 fathoms 

 a sediment essentially consisting of silica, red oxide of iron, 

 and alumina. The two formations pass into each other by 



* The naturalists of tlie ' Challenger ' are silent on this point : on the 

 contrary, they mention that Pidihinlina Mniardi, which largely contri- 

 butes to the formation of the ooze, is very abundant at the surface, and 

 still more so during the day at a depth of from 10 to 20 fathoms. 



t Iliickel has thrown out the suggestion that the spines with which 

 Orhidina and Glohiyerina are crowded " probably contribute essentially 

 to enable these little animals to float below the surface of the water by 

 greatly increasing their surface, and consequently their friction against 

 the water, and rendering it more difficult for them to sink." But the 

 force of this suggestion is altogether weakened by the fact that I'ulvinu- 

 liiKr, equally considered to be surface-swimmers, do not possess any 

 spines. 



