822 



FORMS OF ANIMAL LIFE 



Author, however, from his own examination of the Globigerina ooze, 

 is of opinion that the shells forming its surface-layer must live on the 

 Bottom, being incapable of floating in consequence of their weight ; 

 and that if they have passed the earlier part of their lives in the 

 upper waters they drop down as soon as the calcareous deposit con- 

 tinually exuding from the body of each animal, instead of being em- 

 ployed in the formation of new chambers, is applied to the thicken- 

 ing of those previously formed. That many types of Foraminifera 



pass their whole lives at 

 depths of at least 2,000 

 fathoms is proved, in regard 

 to those forming calcareous 

 shells, by their attachment 

 to stones, corals. Arc. ; and 

 in the case of the arena- 

 ceous types by the fact that 

 they can only procure on tin- 

 bottom the sand of which 

 their ' tests ' are made up. 



A very remarkable type 

 has recently been discovered 

 adherent to shells and corals 

 brought from tropical seas. 



to which the name 

 teria has been given. This 

 may be regarded as a highly 

 developed form of Globi- 

 gerina, its first formed por- 



Fio. 621.-Gloli!/<;-hi, as captured by tow-net tion living all the essential 

 floating at or near surface. characters of that genus. 



It grows attached by the 



apex of its spire, and its later chambers increase rapidly in size, 

 and are piled on the earlier in such a manner as to form a depressed 

 cone with an irregular spreading base. The essential character of 

 Globigerina the separate orifice of each of its chambers is here re- 

 tained with a curious modification; for the central A vst ilmle into 

 which they all open forms a sort of vent whose orifice is at the apex 

 of the cone, and is sometimes prolonged into a tube that proceeds 

 from it ; and the external wall of this cone is so marked out by 

 septal bands that it comes to bear a strong resemblance to a minute 

 /lulu H n.x (acorn-shell), for which this type was at first mistaken. The 

 principal chambers are partly divided into chamlierlels by incomplete 

 partitions, as we shall find them to be in Ko;oun. The presence of 

 sponge-spicules in large (|uantity in Ilie chambers of many of the 

 best preserved examples of this type was for some time a source of 

 perplexity ; but this was explained by the lale Professor Max 

 iSchiilt/.e, 1 who .showed hou the pseudopodia of this rhi/opod have 

 t he habit, like those of Hcdiphysema, of taking into themselves >ponge- 

 spicules. which they draw into the chambers, so that 1 hex liecome 

 incorporated with the sarcode-body. It should he added that Pro- 

 1 Archiv f. \n/iirt/i'nc!i. \.\i\. 1st;:-!, p. 81. 



