FORAMINIFERA AND RADIOLARIA. 



81 



475. Lituolida. The type of this family, which is named after it, is 

 a large, sandy, many-chambered fossil form occurring in the Chalk, to 

 which the name Lituola was given by Lamarck, from its resemblance in 

 shape to a crozier. A great variety of recent forms, mostly obtained by 

 deep-sea dredging, are now included in it; as bearing a more or less close 

 resemblance to it and to each other in their chambered structure, and in 

 the arrangement of the sand-grains of which their tests are formed. 

 These grains are, for the most part, finer than those of which the tests 

 of the preceding family are constructed, and are set (so to speak) more 

 artistically; and a considerable quantity of a cement exuded by the ani- 

 mal is employed in uniting them. This is often mixed up with sandy 

 particles of extreme fineness, to form a sort of ' plaster ' with which the 

 exterior of the test is smoothed off, so as to present quite a polished sur- 

 face. It is remarkable that the cement contains a considerable quantity 

 of oxide of iron, which imparts a ferruginous hue to the * tests ' in whicn 

 it is largely employed. The forms of the Lituoline ' tests ' often simulate 

 in a very curious way those of the simpler types of the Vitreous series. 



FIG. 321. 



Arenaceous Foraminifera: a, 6, Exterior and sectional views of Reophax rudis; c, Bhabdam- 

 mina abyssorum ; d, cross section of one of its arms; e, Reophax scorpiurus; f, Hormosina Car- 

 penteri. 



Thus, the long, spirally coiled undivided sandy tube of Ammodiscus 

 is the isomorph of Spirillina ( 479). In the genus Halophragmium 

 (Fig. 320 a, b), we have a singular imitation of the Globiyerine type; and 

 in TJiurammina papillata (Fig. 320, </) a not less remarkable imitation 

 of the Orluline. This last is specially noteworthy for the admirable 

 manner in which its component sand-grains are set together; these being 

 small and very uniform in size; and being disposed in such a manner as 

 to present a smooth surface both inside and out (Fig. 320, 7i), whilst 

 there are at intervals nipple-shaped protuberances, in every one of which 

 there is a rounded orifice. A like perfection of finish is seen in the test 

 of Hormosina ylobulifera (Fig. 320, c), which is composed of a succession 

 of globular chambers rapidly increasing in size, each having a narrow 

 tubular neck with a rounded orifice, which is received into the next seg- 

 ment. Iii other species of the same genus, there is a nearer approach to 



