30 



INVERTEBRATE AXLMALS, 



the aarcode is exposed, whether this be only at the mouth of the 

 shell, as in Miliola (fig 9, 6), or whether it be over the whole 

 surface, as in Discorhina (fig. 9, c), it has the power of giving off 

 pseudopodia. The pseudopoilia, however, diff'er greatly from those 

 of the Amoeba, and they show some remarkable characters. They 

 are extremely long thread-like processes, instead of being blunt and 

 finger-shaped (fig. 8, 6), and they have the curious property that they 

 run into one another and interlace towards their extremities, so as 

 to form a network which has been aptly compared to an " animated 

 spider's web." Lastly, the microscope reveals in the pseudopodia 



vv^VV'v]>,^;i# 



Fig. 9. — Morpholcgy of Foraminifera. a Lagerui' vulgaris, a iiionotlialainous Foram- 

 inifer ; & jyHliola (after Schultze), showing the pseudopodia protruded from the oral 

 aperture of the shell ; c Discorhina (after Schultze), showing the nautiloid shell v.ith 

 foramina in tlie shell-walls, giving exit to pseudopodia ; d Section of Nodosaria 

 (after Carpenter): f Xodosoria hi^pida ; / Glohigerina buUoides. 



a very curious circulation of minute solid particles or granules, which 

 travel in all directions through the pseudopodial network. Inter- 

 nally, the sarcode-body of the Foraniiitifera is of a very simple 

 structure ; but a nucleus and contractile vesicle are usually, if not 

 invariably, pi'esent. 



Simple as is the sarcode-body of the Foramiinfira, it has in all 

 cases the jjower of secreting a skeleton or. shell, which is technically 

 called the " test " (Lat. testrj,, a shell). The shell is usually " calcare- 

 ous " — that is to nay, composed (jf carbonate of lime ; but it is some- 

 times ''arenaceous," or composed of jjaiticlesof sand united too-ethcr 



