RECENT EESEARCHES ON THE RADIOL ARIA. 



137 



was, at the time, a complete and exhaustive account, yet, were it 

 even readily and generally accessible, important additions have 

 now been made to our knowledge of these animals since its pub- 

 lication. I venture to think therefore, and my opinion has been 

 confirmed by very high authority (that of our esteemed Presi- 

 dent), that an account of these beautiful, and in many respects 

 complex, organisms will not be an unwelcome addition to English 

 zoological literature. 



Under the name Badiolaria are comprised a great number of 

 minute, very varied, and beautiful organisms which are found 

 swimming near the surface of the water, and which considerably 

 resemble the Heliozoa, but are of more complex structure. 



Each individual consists of two portions of coloured or colour- 

 less Barcode — one portion nucleated and central, the other portion 

 peripheral and almost always containing certain yellow cells. 

 These two portions are separated by a porous membrane called 

 the capsule* ; and the whole is invested by a generally very deli- 

 cate gelatinous layer. The sarcode, moreover, sends forth, mostly 

 on all sides, multitudinous radiating, filamentary prolongations 

 of its substance, the pseudopodia, which may or may not branch 

 or anastomose. 



In most species skeletal structures are developed in the sarcode 

 either outside or inside the capsule, or both without and within 

 it, and generally in the form of spheroidal investing networks, or 

 of radiating spines, or of combinations of these, though sometimes 

 reduced to a few filamentar}^ or branched spicula. Whatever its 

 form, the skeleton is almost always siliceous, and is never calca- 

 reous t- 



The individuals (or zooids) of some species, both of kinds pro- 

 vided with and others destitute of skeletal structures, naturally 



* Sir C. Wyyille Thomson speaks of Eadiolarians destitute of a central 

 capsule ('Voyage of the Challenger,' vol. i.). If this is not a clerical error, 

 some very interesting new forms may be expected to be made known by the 

 publication of the ' Challenger's ' zoology. But whatever novelties may be 

 forthcoming, forms without a central capsule should, I think, be excluded from 

 the Radiolaria. 



t The calcareous bodies found in the extracapsular sarcode of Myxobrachia 

 I do not regard as forming a real exception. As to the calcareous forms noticed 

 and figured by Sir C, Wyville Thomson ('Voyage of the Challenger,' vol. i. 

 p. 233) under the name of Calcaromma calcarea, we must wait for more de- 

 tailed and exact information. I cannot but think it possible that its calcareous 

 particles may really be extraneous bodies, as also those of Mt/xohrachia. 

 LINX. JOURN. — ZOOLOGY, YOL. XfV. 10 



