Jan. 24, 1884] 



NATURE 



297 



sule membrane spherical, pierced on all sides by innumerable 

 fine pores. Extracapsularium, a voluminous gelatinous sheath, 

 without phseodium, usually without zooanthclla. Skeleton always 

 intracapsular, consisting of acanthine spicules, which meet in the 

 centre of the central capsule, and pierce the membrane. 



lA. Sub-order I. Acanthometrce, J. Muller, 1858. Acan- 

 tliaria, in which the acanthine skeleton is c imposed merely of 

 r.adial spicules, but does not fuim a fenestrated diiell. 



Family i. Actinelida, Hkl., 1865. Skeleton composed of a 

 varyinjj number of spicules, not distributed according to J. 

 Muller's law i^Astrolopkida^ LUholophida) , 



Family 2. Acanthonida, Hkl., 1S81. Skeleton composed of 

 twenty radial spicules, distributed regularly according to J. 

 Midler's law, in five quadriradiate zones {Acanthometrida, 

 Acanthcstaurida, Acaittholonchida). 



IB. Sub-order II. Acanthophracta;, Hertvvig. Acantharia, 

 in which the skeleton is composed of twenty radial spicules 

 regularly distributed according to J. Muller's law, and forming 

 a fenestrated or solid shell round the central capsule by means of 

 connected transverse processes. 



Family 3. Dorataspida, Hkl., 1862. Fenestrated shell, 

 spherical, spheroidal, or ellipsoidal, simple or double (Phract- 

 aspida, Spharocapsida, P/trac/opelmida. 



Family 4. Diploconida, H., 1S62. Shell shaped like an 

 hour-glass or a double cone, having in its axis a pair of strong 

 spicules running in opposite directions {Diploconus), 



2. Order II. Spumellaria, Ehrenberg (= Peripylca -I- 

 T/ialasiicollea + Sphwrozoea, Hert»\ig, 1879 = Splnerellaria 

 -t- Collodaria 4- Polycytlaria, Hkl., 18S1). 



Central capsule originally (and usually permanently) spheri- 

 cal, more rarely discoid or polymorph<jus. Nucleus usually 

 divided only immediately before the formation of spores into a 

 immber of small nuclei. Capsule membrane simple, pierced on 

 all sides by innumerable fine pores. Extracapsularium a volu- 

 minous gelatinous sheath, without phreodium, usually with 

 zooxanthella. Skeleton consisting of silicium, or of a silicate, 

 originally usually forming a central reticulate sphere, later 

 extremely polymorphous, more rarely rudimentary or entirely 

 wanting. 



2A. Sub-order III., Collodaria, H., iSSi (sensu amplion), 

 Spumellaria without skeleton, or with a rudimentary skeleton 

 composed mainly of detached siliceous spicules scattered outside 

 the central capsule. 



Family 5. ThalassicoUida, H., 1862. Skeleton entirely 

 wanting. Central capsules living solitary, monozjic [Aclissa, 

 Thalassolampe, Thalassicolla, &c. 



Family 6. CoUozoida, H., 1862. Skeleton entirely wanting. 

 Central capsules tocial, thickly embedded in a common gela- 

 tinous body, polyzoic (CoUozoum), 



Family 7. Thalassosphierida, H., 1862. Skeleton composed 

 of numerous detached spicules, scattered round the solitary 

 central capsule. Monozoic (TAalassosp/itera, Thalaaoxanihium, 

 &c.). 



Family 8. Spha:rozoida. Skeleton composed of numeroui 

 detached spicules, scattered round the social central capsules, or 

 embedded in their common gelatinous body (Sp/iarozoum, 

 Rhapidozoum), 



2B. Sub-order IV. Spheerellaria, Hkl., 1881. Spumellaria 

 having a reticulate or spongiose siliceous skeleton, forming a 

 single connected plexus of siliceous fibre, originally evolved 

 from a simple fenestrated sphere. 



Family 9. Sphaeroida (vel Sphceridca, H., 1879. " Protis- 

 tenreich,"p. 103 ; "Prodromus," 1881, pp. 448, 449). Skeleton 

 either a simple fenestrated sphere, or composed of several con- 

 centric fenestrated spheres, with or without radial spicules. 

 Central capsule solitary, monozoic. The family of Spumellaria 

 richest in specific forms {MonospAuria, Diosphwria, Triospharia, 

 Telraspharia, Polyspharia, SpongosphiCiid). 



Family 10. Collosphoerida, H. , 1S62. Skeleton either 

 simple reticulate spheres, or composed of two concentric 

 reticulate spheres, severally inclosing the spherical, social, 

 central capsules. Polyzoic (Acrospharidj, Clal/iro^p/iarida). 



Family 11. Pylonida, Hkl., 1881 {"Prodromus," p. 463). 

 Skeleton subspherical, ellipsoid, or polymorphous, distint^uLsh^d 

 by large fissures or gaps, which break through the originally 

 spherical or ellipsoidal fenestrated shell, at definite p-.iuts. 

 Fenestrated shell, simple or composed concentrically, with or 

 without spicule . Geometrical fundamental form with three 

 unequal, equipolar axes, perpendicular one to another {Pylocas- 

 pidUy Pylophonnida). 



Family 12. Zygastida, Hkl., 1881. Skeleton an ellipsoidal 

 or almost cylindrical fenestrated shell prolonged in the direction 

 of one axis and constricted annularly in the middle, perpendicu- 

 lar to the said axis, often articulated liy repeated annular stric- 

 tures. One or two concentric, small, fenestrated shells, often 

 inclosed in the middle. Both poles of the principal axis equal 

 (Arliscida, Cyphinida). 



Family 13. Li'JicHd.i, Hkl. \''Monogr. Prodrom." l88i,p. 46.-1). 

 Skeleton spheroidal or irregular, composed of a small, central, 

 fenestrated sphere, and of series or heaps of chambers piled 

 round it, sometimes spirally or axially according to definite, 

 complicated laws, sometimes quite irregularly (P/wrticida, Sor- 

 eumida, Spiretimida). 



Family 14. Discoida (vel Discidm, Hkl., 1879, " Protisten- 

 reich," p. 103, " Prodrom." p. 456). Skeleton flattened like a disk, 

 originally circular, lenticular, later often polymorphous by 

 means of peripheric processes ; sometimes distinctly composed 

 of rings, sometimes spongiooC {^Plusodiscidaf Coccodisciduy Poro- 

 discida, Spon^odiscida). 

 ■ 3. Order III. Nassellaria, Ehrenberg (= Monopylea, 

 Hertwig, 1S79 ; Monopylaria, HUl., 1881). 



Central capsule originally invariably uniaxial, oval, or conical, 

 with two different poles of the axis ; at one pole the character- 

 istic porous area through which the whole of the pseudopodia 

 project like a bush. Nucleus usually divided late, immediately 

 before the formation of spores, into numerous s.nall nuclei. 

 Capsule membrane simple. Extracapsularium, a voluminous 

 gelatinous sheath without phsodiuui, usually without zooxan- 

 thellae. Skeleton consisting of silicium or of a silicate, originally 

 (it is probable universally) a ring or a triradiate framework of 

 spicules, later extremely polymorphous, usually forming a di- 

 pleuric fenestrated shell (wanting only in the simplest form, 

 Cystidium). 



3A. Sub-order V., Plectellaria, Hkl. Nassellaria, in which 

 the skeleton consists of a simple siliceous ring or of a triradiate 

 framework of spicules, usually furnished with processes forming 

 simple or branched spicules. The branches of the latter may 

 be united into a loose plexus, without, however, forming a cham 

 bered fenestrated shell. The s'l^eleton is entirely wanting only 

 in the simplest form (Cyslidium). 



Family 15. Cystidina, Hkl, nov. fam. Skeleton entirely 

 wanting (Cystidium). 



Family i5. Plectoida (vel Plagonida.), Hk'., 1881. Skeleton 

 originally composed of three spicules or siliceous rods, radiat- 

 ing from one point (near the mouth of the central capsule), the 

 latter often ramifying into loose plexus (Plagonida, PUctanida). 



Family 17. Stephoida (vel Stephaitida), Hkl., 1S81. Skele- 

 ton originally (?) forming a simple siliceous ring (with or without 

 spicules), later often several connected siliceous rings or a loose 

 plexus, not, however, developed into a regular fenestrated shell 

 Monoshphida, Parastephida, Dyosttphida, TriosU-phida). 



lb. Sub-order VI. Cystellaria (Hkl., 1881). Nassel- 

 laria, having a chaoibered (usually dipleuric) fenestrated shell, 

 the primary foundation of which consists either of a simple 

 ring (like the Stephoida), or of a triradiate framework (like the 

 Plectoida), sometimes of a combination of both. Primary 

 foundation sometimes entirely lost. 



Family 18. Spyroida (vel Sphyridina, Ehrenberg). Skeleton 

 dipleuric, forming a fenestrated twin-shell, the two halves of 

 which (right and left chamber) are connected by a vertical ring, 

 lying in the median plane. At the upper (aboral) pole of the 

 longitudinal axis, usually an occipital apical thorn, at the lower 

 (oral) pole an oscular netuork, with four (rarely three, five, or 

 more) operangs, and three (rarely more) spicules, (Triospyiida, 

 Diorpyrida, Tdiaspyrida, Penta^pyrida, Polyspyrida, Peri- 

 spyrida, Plcurospyridd) — Zygocystida. 



Family ig. Botryoida (Hkl., 1881 = Polycystida, 1862). 

 Skeleton an irregular fenestrated shell, composed of several 

 unequal chambers, piled usually irregularly (rarely in definite 

 order varying from that of the Cyrtida) round a primary 

 capitulum (derivable from the twin shell of the Spyroida), with 

 or without spicules (Pyloboiiyida, Cannobolryida). 



Family 20. Cyrtida, Hkl., 1S62. Skeleton, dipleuric (at least 

 originally), consisting either of a primary capitulum (derivable 

 from the twin-shell of the Spyroida ?) or (usually) of one or 

 more chambers, joined to the oral pole of the said capitulum in 

 the longitudinal axis. Osculum sometimes open, sometimes 

 reticulate. Usually three radial spicules (one median and two 

 lateral), rarely four or mjre spicules, or none at all (having 

 undergone retrograde formation ?). The family most rich in 



