45° 



NATURE 



{March n, 1880 



principal opening and two smaller lateral openings 

 (Tripylea), while others have a larger number of openings 

 regularly or irregularly disposed (SporopylecE). Notwith- 

 standing its peculiar structure and conspicuous size, the 

 central capsule of all Phaeodaria, has merely the histological 

 value of a single simple cell. This is shown by the micro- 

 chemical condition of its protoplasmic contents and the 

 nucleus inclosed within it. This cell-nucleus (described 

 by me in 1862 as the " inner vesicle") is vesicular and of 

 large size, being usually more than half the diameter of 

 the central capsule. It sometimes includes one large 

 nucleolus, sometimes several. 



The extra-capsular soft substance of all Phaeodaria is 

 distinguished by two characteristic peculiarities — first, by 

 the large quantity of the extra-capsular sarcode, which is 

 more voluminous than the intra-capsular, and secondly 

 by the mass of phasodella or " dark pigment granules " 

 which it contains. The colour of the latter is usually 

 dun-brown or black-brown, often greenish or dun-green. 

 The layer which originates the pseudopodia is very thick 

 and inclosed in a thick jelly, often traversed by spaces 

 through which the ray-like pseudopodia protrude. The 

 Phasodella or peculiar pigment-granules of which the large 

 Phseodium is composed, are, like the Phaeodium, of varying 

 form and size. Sometimes the Phaaodium envelopes the 

 greater part of the capsule, sometimes only one side of it. 

 The extra-capsular yellow cells which are found in all 

 typical Radiolaria are entirely wanted in the Phaeodaria. 



The siliceous skeleton is extra-capsular in all Phaeodaria 

 and is very peculiar in form and structure. Although the 

 principal types of this group have corresponding repre- 

 sentatives among the typical Radiolaria, they are usually 

 easily distinguished from the latter. In a small division 

 only, corresponding to the Thalassicollidae, the siliceous 

 skeleton is entirely wanting (Phaodinida). All other 

 Phaeodaria have a characteristic siliceous skeleton, accord- 

 ing to the structure of which I distinguish in the group 

 four orders and ten families. 



Order I. Ph^eocystia. — The siliceous skeleton is either 

 entirely wanting or it consists of hollow spines, arranged 

 sometimes irregularly, sometimes regularly, outside the 

 central capsule. 



Family 1. PHiEODlNID.'E. — Siliceous skeleton entirely 

 wanting. Genera : Phaodina, Plia-ocolla. 



Family 2. Cannorhaphid^e. — The siliceous skeleton 

 consists of numerous separate hollow spines, or portions 

 of hollow network, which, scattered round the periphery 

 of the extra-capsular soft substance, are usually arranged 

 tangentially. Genera : Cannorhaphis, Thallassoplancta, 

 Diciyocha. 



Family 3. Aulacanthid/E. — The siliceous skeleton 

 consists of hollow radial spines, which spring from the 

 outer surface of the central capsule, and traverse the extra- 

 capsular jelly. The outer surface of the jelly is usually 

 covered by a thick mantle of fine hollow siliceous needles, 

 which are arranged tangentially and felted together. 

 Genera : Aulacantha, Attlaneora, Aulographium. 



II. Order. Ph^eogromia. — The siliceous skeleton 

 consists of a single fenestrated shell which is of different 

 forms, sometimes round, sometimes egg-shaped, often 

 dipleuric, but always furnished with a large principal 

 opening or mouth (more rarely with several openings). 

 Hollow spines with peculiar pore-areas at their bases are 

 often present. 



Family 4. Challengerid^. — The siliceous skeleton 

 consists of a fenestrated shell, uniaxial or dipleuric, often 

 laterally compressed and carinated, often egg-shaped or 

 oval, and furnished with a wide opening at one end of the 

 axis. This mouth is seldom simple, it is usually armed 

 with a hollow tooth, or with one or more, often branched 

 hollow tubes. The fenestrated structure of the siliceous 

 shell resembles most closely that of the diatoms ; there is 

 a fine pore in the middle of each of the hexagonal facets 

 (Comp. Murray, 1876, I.e., PI. 24, Figs. I, 2, 4). Genera : 



Challengeria, Tuscarora, Gazelletta, Porcupinia, Ento- 

 canula, Lithogromia. 



Family 5. CastanelliDjE. — The siliceous skeleton con- 

 sists of a simple round fenestrated shell, which has in 

 one part of its upper surface a wide opening, often sur- 

 rounded by peculiar processes. The fenestrated shell is 

 usually ornamented with solid or hollow spines. Genera : 

 Casianella, Castanidium, Castanissa, Castanopsis, Casta- 

 mtra. 



Family 6. ClRCOPORID<£. — The siliceous skeleton 

 consists of a sub-spherical or polyhedral siliceous shell, 

 from which radiate in different directions hollow tubes 

 (simple or branched, often provided with whorls of cilia). 

 The shell has a large opening, as well as scattered pore- 

 facets. The pores usually form circles round the bases of 

 the spines. (Comp. Murray, 1876, I.e., PI. 24, Fig. 5-6). 

 Genera : Circoporus, Circospathis, Ciicostephanus, Poro- 

 stephaniis, Porospathis. 



Order III. Ph;eosph;eria. — The siliceous skeleton 

 consists of numerous hollow tubes which are combined 

 in a peculiar manner into a large, usually round or poly- 

 hedral fenestrated body. 



Family 7. Aulosph. j erid;e. — The siliceous shell is a 

 fenestrated ball or a fenestrated polyhedral body whose 

 latticework is foimed of hollow tubes. Hollow spines 

 usually radiate from the points of connection of the lattice- 

 work (Comp. Haeckel, " Monogr. der Radiol.," 1862, p. 

 357, Taf. x. xi.). Genera: Aulosphara, Aulodictyum, 

 Aitloplegma. 



Family 8. CannospH/ERID.E.— The siliceous skeleton 

 consists of a uniaxial globular or oval simple bounding 

 shell, which is connected by means of hollow radial rods 

 with a composite outer encrusting shell. The outer shell 

 consists of hollow tubes, which form a wide-meshed 

 latticed sphere ; hollow simple or branched radial spines 

 spring from the junctions of the lattice (Comp. Hertwig, 

 I.e., 1879, p. 91, PI. ix.). Genera: Cannacaidha, Canno- 

 sphara, Caloctudha. 



Order IV. Ph.eoconxhia. — The siliceous skeleton con- 

 sists of two separate fenestrated shells, like those of a 

 bivalve mollusc. Simple or branched hollow tubes are 

 often found at the junction of the valves. 



Family 9. Concharid.e. — The siliceous skeleton con- 

 sists of two semicircular or lenticular fenestrated shells 

 turned each to each with the concavities inwards ; the 

 edges of the shells are usually set with rows of teeth, 

 which lock together like the teeth of a bivalve (Comp. 

 Murray, 1876, I.e., PI. 24, Fig. 3). Genera: Concharium, 

 Conclwpsis, Conehidiutn, Conchocaras. 



Family 10. Celodendrid/E.— The siliceous skeleton 

 consists of two semicircular or lenticular fenestrated shells 

 with the concave sides turned towards each other. Simple 

 or tree-like branched hollow spines spring from the two 

 opposite poles of the principal axis, or from the centre of 

 the junction of the hemispheres. (Haeckel, " Monogr. 

 d. Rad.," 1862, p. 360; Taf. xiii., Figs. 1-4; Taf. xxxn., 

 Figs. 1-3.) Genera : Calodeyidrum, Calothamnus, Ceelo- 

 dryimts, Ccelothaitma. 



Taking a comparative survey of the organisation of the 

 known Phaeodaria, we can define the characters of this 

 group of Rhizopoda as follows : — 



The Phaeodaria are single-celled Rhizopods, whose 

 larger cell-body (the central-capsule) incloses a large 

 nucleus (or inner-vesicle). The cell-membrane is always 

 double, pierced bv one or more large openings, through 

 which the intra-capsular protoplasm communicates with 

 the much more abundant extra-capsular protoplasm. In 

 the latter, towards the outside, lies the phasodium, a 

 peculiar thick mass of dark pigment-granules (or phaeo- 

 della). The whole body is inclosed in a thick gelatinous 

 covering, which is often provided with spaces which the 

 numerous pseudopodia traverse in order to rediate freely 

 beyond its outer surface. With very few exceptions 

 (Phaeodinideae) a well-developed, always extra-capsular 



