IV THE VOYAGE OF H.M.S. CHALLENGEE. 



perforated by numerous fine pore-canals, which are regularly distributed in series or 

 groups, but without a larger principal opening (osculum). (2) The Nucleus is always 

 excentric and generally precocious, since it divides early by a peculiar process of 

 budding into numerous small nuclei. (3) The Pseudopodia are very numerous and 

 distributed regularly in groups (or series united into a network). (4) The Calymma 

 contains no phseodium. (5) The Skeleton is generally present, always centrogenous, and 

 composed of acanthin. (6) The Ground-form of the central capsule is originally 

 spherical (often modified), that of the skeleton polyaxon (often modified). 



8. Monopylea or Nassellaria. — Those Radiolaria which we call "Monopylea" from 

 the formation of their central capsule, or " Nassellaria " from the nature of their 

 skeleton, are distinguished from the other three legions of the class by the combination 

 of the following constant characters : — (1) The Membrane of the central capsule is single, 

 and has only one large principal opening (osculum) at the basal pole of the vertical main 

 axis ; this osculum is closed by a perforated lid (porochora or operculum porosum) from 

 which there arises within the central capsule a peculiar cone of threads or pseudopodia 

 (podoconus). (2) The Nucleus is usually excentric and is always serotinous, since it 

 only divides at a comparatively late period into spore-nuclei. (3) The Pseudopodia are 

 not very numerous and arise by division of a single stem or bundle of threads of sarcode, 

 which issues from the porochora. (4) The Calymma contains no phseodium. (5) The 

 Skeleton (very rarely absent) is never centrogenous, but always extracapsular and 

 siliceous. (6) The Ground-form of the central capsule is always monaxon (with a vertical 

 allopolar main axis), originally ovoid, often modified ; that of the skeleton is also generally 

 monaxon, often modified (triradial or bilateral). 



9. Cannop)ylea or PhcBodaria. — -Those Radiolaria which we call " Cannopylea " from 

 the constitution of their central capsule, or " Ph^odaria " on account of their peculiar 

 phseodium, are distinguished from the other three legions by the combination of the 

 following characters : — (l) The Membrane of the central capsule is double, consisting of a 

 strong outer and delicate inner capsule, and has only one principal opening (osculum) at 

 the basal pole of the vertical main axis ; this osculum is closed by a radiate cover (astropyle 

 or operculum radiatum), from the centre of which arises an external tubular sj)Out 

 (proboscis). Occasionally a few small accessory openings parapylse) are present besides 

 the principal opening. (2) The Nucleus lies centrally or subcentrally in the capsule (in 

 the vertical main axis), and is serotinous, inasmuch as it only divides at a late period 

 into spore-nuclei. (3) The Pseudopodia are usually very numerous and arise from a 

 thick sarcomatrix, formed by the spreading out of a thick stem of sarcode, which issues 

 from the astropyle. (4) The Calymma always contains a phseodium or peculiar 

 voluminous excentric mass of pigment. (5) The Skeleton (very rarely absent) is never 

 centrogenous, always extracapsular and formed of a sUicate of carbon. (6) The Ground^ 



