RECENT RESEARCHES OX THE RADIOLARTA. 1 iO 



detached parts. Now if we conceive these to be united together 

 into one complex structure, we may thence derive all the other 

 forms of circumferential Radiolarian skeletons. First, by union 

 in an irregular manner, we obtain a spheroidal investing network 

 with irregular intervals, as in Ci/rtidosphcera and CoUosphcBra. 



Secondly, let these be united with regularity, and we get such 

 a form as HeUosplicera inermis * (the skeleton of which consists of 

 bars enclosing equal-sized and perfectly regular hexagonal spaces); 

 and if the skeletal parts be hollow, we get such a structure as 

 Aulosphcsra elegantissima f. 



Thirdly, let the intervals of the network be greatly reduced in 

 relative size, as sometimes in Collosplicera J, and the sphere be 



Fig. 6. 



Dictyopodium, sp. ? (After Wjv. Thomson.) § 



* L. c. pi. ix. fig. 1 . t X. c. pi. xi. fig. G. I L. c. pi. xxxiv. fig. 4. 



§ I herewith take the opportunity of acknowledging the kindness of Prof. Sir 

 C. Wyville Thomson and Messrs. McMillan & Co., in allowing me the use of 

 woodcuts fig. 6 and fig. 8 hereafter represented. Both these have already 

 ;ippoared in the 'Voyage of the Challenger.' 



