FORAMINIFERA AND RADIOLARIA. 



115 



tions. The e capsule ' is pierced by the pseudopodia, whose convergence 

 may be traced from without inwards, after passing through it; and it is 

 itself enveloped in a layer of less tejiacious protoplasm, resembling that 

 of which the pseudopodia are composed. One species, the Acantliometra 

 echinoides, which presents itself to the naked eye as a crimson-red point, 

 the diameter of the central part of its body being about 6-1000ths of an 

 inch, is very common on some parts of the coast of Norway, especially 

 during the prevalence of westerly winds; and the Author has himself 

 met with it abundantly near Shetland, in the floating brown masses 

 termed madre by the fishermen (who believe them to furnish food to the 

 herring), which consist mainly of this Acanthometra mingled with 

 Entomostraca. 



506. Cpllozoa. To this group belong these remarkable composite 

 forms, which, exhibiting the characteristic Radiolarian type in their indi- 

 vidual zooids, are aggregated into masses in which the skeleton is repre- 



Fio. 349. 



FIG. 350. 



Haliomma Humboldtii. 



Sphcerozoum ovodimare. 



sented only by scattered spicules, as in Sphcerozoum (Fig. 350) and 

 Thalassicolla. These ' sea-jellies/ which so abound in the seas of warm 

 latitudes as to be among the commonest objects collected by the Tow-net, 

 are small gelatinous rounded bodies, of very variable size and shape, but 

 usually either globular or discoidal. Externally they are invested by a 

 layer of condensed sarcode, which sends forth pseudopodial extensions 

 that commonly stand out like rays, but sometimes inosculate with each 

 other so as to form network. Towards the inner surface of this coat are 

 scattered a great number of oval bodies resembling cells, having a toler- 

 ably distinct membraniform wall and a conspicuous round central nucleus. 

 Each of these bodies appears to be without any direct connection with 

 the rest; but it serves as a centre round which a number of minute yel- 

 lowish-green vesicles are disposed. Each of these groups is protected by 

 a siliceous skeleton, which sometimes consists of separate spicules (as in 

 Fig. 350), but which may be a thin perforated sphere, like that of cer- 

 tain Polycystina, sometimes extending itself into radial prolongations. 



