Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/871

Rh RETICULARIA.] PROTOZOA 847 Orbicxlina, Lamarck ; Orbitolites, Lamarck (by a division of the chambers regularly into chamberlets, and a cyclical mode of growth which results in shells of the size of a shilling, a very elaborate- looking structure is produced which has been admirably analysed by Carpenter (40), to whose memoir the reader is specially referred). FIG. Xl.Miliolina (Trifoculina) tenera. Young 1 ving animal with ex panded pseudopodia (after Max Schultze). A single nucleus is seen in the innermost chamber. Fain. 5. ALVF.OLTXIXA. Shell spiral, elongated in the line of the axis of the convolution ; chambers divided into chamberlets. Genus. Alveolhin, I/Orb. Fam. 6. KERAMOSPH.ERIXA. Shell spherical ; chambers in con centric layers. Genus. Keramospksera, Brady. ORDER 4. LITUOLTDEA, Brady. Characters. Test arenaceous, usually regular in contour ; septa- tion of the many-chambered forms often imperfect, the cavity being labyrinthic. This order consists of sandy isomorphs of the simpler Miliolidea, and also of the simpler Perforata (Lagena, Nodosaria, Cristellaria, Globigerina, Kotalia, Nonionina, &c. ) ; it also contains some peculiar adherent species. Fam. 1. LITUOLIXA. Test composed of coarse sand-grains, rough externally ; often labyrinthic. Genera. lleophax, Montfort ; Haplophragmium, Reuss (Fig. X. 7); Coskinolina, Stache; Placopsilina, D Orb. ; Haplostiche, Reuss; Lituola, Lamarck; BdeUoidina, Carter. Fam. 2. TROCHAMMIXIXA. Test thin, composed of minute sand-grains incorporated with calcareous and other organic cement, or embedded in a chitinous membrane ; exterior smooth, often polished ; interior smooth or rarely reticulated ; never labyrinthic. Genera. Thurammina, Brady (test consisting typically of a single spherical chamber with several mammillate apertures, Fig. X. 5, 6) ; Hippocrepina, Parker ; Hormosina, Brady ; Ammo- discus, Reuss ; Troefiammina, Parker and Jones ; Carterina, Brady; WcWma, D Orb. Fam. 3. EXDOTHYRINA. Test more calcareous and less sandy than in the other groups of Lituolidea ; sometimes perforate ; septation distinct. Genera. Xodosinclla, Brady; Polyphragma, Reuss; fnvolutina, Terq. ; Endothyra, Phillips ; Bradyina, Moll. ; Stachda, Brady. Fam. 4. LOFTUSIXA. Test of relatively large size ; lenticular, spherical, or fusiform ; constructed either on a spiral plan or in concentric layers, the chamber cavities occupied to a large extent by the excessive development of the finely arenaceous cancellated walls. Genera. Cyclammina, Brady ; Loftusia, Brady ; Parkeria, Carpenter. Sru-CLASs B. Perforata. Characters. Shell substance perforated by numerous minute apertures, through which as well as from the main aperture the protoplasm can issue. ORDERS. TEXTULARIDEA, Brady. Characters. Tests of the larger species arenaceous, either with or without a perforate calcareous basis ; smaller forms hyaline and conspicuously perforated. Chambers arranged in two or more alternating series, or spiral or confused ; often dimorphous. Fam. 1. TEXTUIARINA. Typically bi- or tri-serial ; often bi- rarcly tri-morphous. Genera. Textularia Defrance ; CuneoUna, D Orb. ; Verneiul- ina, D Orb.; Tritaxia, Reuss; Chrysalidina, D Orb.; Bigenerina, D Orb. ; Favonina, D Orb. ; Spiroplecta, Ehr. ; Gaudryina, D Orb. ; Valvulina, D Orb.; Clavulina, D Orb. Fam. 2. BULIMINIXA. Typically spiral ; weaker forms more or less regularly biserial ; aperture oblique, comma-shaped or some modification of that form. Genera. Bulimina, D Orb. ; Virgulina, D Orb. ; Bifarinn, Parker and Jones ; Bolivina, D Orb. ; Pleuroslomella, Reuss. Fam. 3. CASSIDULINA. Test consisting of a Textularia-like series of alternating segments more or less coiled upon itself. Genera. Cassidulina, D Orb.; Ehrenbcrgina, Reuss. ORDER 6. CHILOSTOMELLIDEA, Brady. Characters. Test calcareous, finely perforate, many-chambered. Segments following each other from the same end of the long axis, or alternately at the two ends, or in cycles of three, more or less embracing. Aperture a curved slit at the end or margin of the final segment. Genera Ellipsoidina, Seguenza ; Chilostomella, Reuss; Allo- morphina, Reuss. ORDER 7. LAGENIDEA, Brady. Characters. Test calcareous, very finely perforated ; either single-chambered, or consisting of a number of chambers joined in a straight, curved, spiral, alternating, or (rarely) branching series. Aperture simple or radiate, terminal. No inter.septal skeleton nor canal system. Fam. 1. LAGEXIXA. Shell single-chambered. Genera. Lagena, Walker and Boys; Nodosarin, Lamk. ; Lin- gulina, D Orb. ; Frondicalaria, Defrance ; Rhabdogonium, Reuss ; Marginulina, D Orb. ; Vaginulina, D Orb. ; Rimulina, D Orb. ; Cristellaria,iia.jrik, ; Amphicoryne,Schiinb, ; Lingulinopsis, Reuss; Flabellina, D Orb. ; Amphimorphina, Neugeb. ; Dental inopsis, Reuss. Fam. 2. POLYMORPHIXIXA. Segments arranged spirally or irregularly around the long axis ; rarely biserial and alternate. Genera. Polymorphic a, D Orb. ; Dimorphina, D Orb. ; Uvigcr- ina, D Orb. ; Sagrina, P. and J. Fam. 3. RAMULIXIXA. Shell branching, composed of spherical or pyriform chambers connected by long stoloniferous tubes. Genus. Ramulina, Rupert Jones. ORDER 8. GLOBIGERINIDEA, Brady. Characters. Test free, calcareous, perforate ; chambers few, inflated, arranged spirally ; aperture single or multiple, con spicuous. No supplementary skeleton nor canal system. All the larger species pelagic in habit. Genera. Globigerina, D Orb. (Fig. XII. 6) : Orbnlina, D Orb (Fig. XII. 8); Hastigerina, Wy. Thomson (Fig. XII. 5); Pul- lenia, P. and J. ; Sph&roidina, D Orb. ; Candeina, D Orb. ORDER 9. ROTALIDEA, Brady. Characters. Test calcareous, perforate; free or adherent. Typi cally spiral and &quot;rotaliform&quot; (Fig. XII. 2), that is to say, coiled in such a manner that the whole of the segments are visible on the superior surface, those of the last convolution only on the inferior or apertural side, sometimes one face being more convex sometimes the other. Aberrant forms evolute, outspread, aeervuline, or irregular. Some of the higher modifications with double chamber- walls, supplemental skeleton, and a system of canals. The nature of this supplemental skeleton is shown in Fig. XII. 2 and 10. Fam. 1. SPIRILLIXIXA. Test a complanate, planospiral, non- septate tube ; free or attached. Genus. Spirillina, Ehr. Fam. 2. ROTALIXA. Test spiral, rotaliform, rarely evolute, very rarely irregular or aeervuline. Genera. Patellina, Williamson ; Cymbalopora, Ha-y ; Discorbina, P. and J. ; Planorbulina, D Orb. ; Truncatulina, D Orb. ; Anomol- ina, P. and J. ; Carpentaria, Gray (adherent) ; Rupertia, Wallick ; Pulvinulina., P. and J. ; Rotalia, Lamk. ; Calcarina, D Orb. [Shell rotaliform ; periphery furnished with radiating spines ; supplemental skeleton and canal system largely developed. This form is shown in a dissected condition in Fig. XII. 10. Outside and between the successive chambers with finely perforated walls a 2, a *, a 4 a secondary shell-substance is deposited by the proto plasm which has a different structure. Whilst the successive chambers with their finely perforate walls (resembling dentine in structure) are formed by the mass of protoplasm issuing from the mouth of the last-formed chamber, the secondary or supplemental- shell substance is formed by the protoplasm which issues through the fine perforations of the primary shell substance ; it is not finely canaliculated, but is of denser substance than the primary shell and traversed by coarse canals (occupied by the protoplasm) which make their way to the surface of the test (c 1, c). In Cal- carina a large bulk of this secondary shell-substance is deposited around each chamber and also forms the heavy club-like spines.] Fam. 3. TIXOPORIXA. Test consisting of irregularly heaped chambers with (or sometimes without) a more or less distinctly spiral primordial portion ; for the most part without any general pseudopodia 1 aperture.