ARENACEOUS FOEAMINIFEKA 



313 



stance of which very fine sand-grains are dispersed. This ' felt ' is 

 somewhat flexible, and its components do not seem to be united by 

 any kind of cement, as it is not affected by being boiled in strong 

 nitric acid ; its tendency, therefore, seems entirely due to the 

 wonderful manner in which the separate silicious fibres are ' laid.' 

 It is not a little curious that these two forms >hould present them- 

 selves in the same dredging, and that there should be no perceptible 

 difference in the character of their sarcode bodies, which, as in the 

 preceding case, have a dark-green hue. The Mfirsipdlri eloni/(it<t 

 (fig. 614, d), on the other hand, is somewhat fusiform in shape. ;ind 

 has its two extremities elongated into tubes, with a circular orifice 

 at the end of each. The materials of the ' tests ' differ remarkably 

 according to the nature of the bottom whereon they live. When 



Fi<;. 014. Arenaceous Foraminif era : u, li, upper and lower aspects of 

 /iJimgiiiiinn globigeriniforme', c, Hormosinu f/lolmJi/frn : </, Miir 

 elongata ; e, terminal portion, and/', middle portion of the same, enlarged ; 

 g, Thitrtinimina papillata ; /(, portion of its inner surface, enlarged. 



they come up with 'Globigerina mud.' in which sponge-spicules 

 abound, whilst sand-grains are scarce, they are almost entirely 

 made up of the former, which are ' laid ' in a sort of lattice-work, 

 the interspaces of which are filled up by fine xmd-gi-ains ; hut when 

 they are brought up from a bottom on which sand predominates, 

 the larger part of the ' test ' is made up of sand-grains mid minute 

 Foraminifera, with here and there a sponge-spicule (fig. 614, d,f). 

 In each case, however, the tubular extensions (one of which some- 

 times forms a sort of proboscis, e, nearly equalling the body itself 

 in length) are entirely made up of sponge-spicules laid side by side 

 with extraordinary regularity. The genus Rhabdammina (Sars) 

 resembles Saccammina in the structure of its 'test.' which is com- 

 posed of sand-grains very firmly cemented together ; but the grains 



