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(e.g., in Carchesium ). Rostellum : small rostrum ; see Rostrum . Rostrum : usually employed in a generalized way, with reference to the apical end of an organism’s body when it has the appearance of a beak or shows a distinctive protuberance of some kind; may bear the cytostome , as in the haptorian Chaenea or a sucking tube as in the rhynchodians ; the apically located perforatorium or boring apparatus might better be referred to by this less specific term. Rule of Desmodexy : see Desmodexy, Rule of . Rules of Nomenclature : see International Code of Zoological Nomenclature . S Saltatorial Cilia : long cilia distributed sparsely around the body (e.g., in Halteria ), often stiff or heavy when not in motion and used in a quick, jerky sort of jumping locomotion. Sanguicolous : living in the circulatory system or blood of the host. Saprobity System : method of classification of aqueous habitats and their contained communi- ties of microorganisms by recognizing both that distinct zones exist with respect to degrees of pol- lution and that these zones provide certain protists as indicator organisms with optimal conditions for their own growth; see Polysaprobic . Sapropelebiotic : see Polysaprobic . Sapropelic : see Polysaprobic . Saprozoic : type of nutrition in which the organism feeds on, takes in, or absorbs food substances in the dissolved state from the surrounding medium, either by active transport or pinocytosis; this osmo- trophic mode is to be contrasted with the carni- vorous, histophagous , holozoic , macrophagous , microphagus , or other feeding or nutritional habits that essentially involve the ingestion of sizable particulate materials, often including whole prey organisms. Scale : typically a small, sometimes complex struc- ture, organic or mineralized, and of a shape char- acteristic for a group; origin, when known, by secretion from the Golgi apparatus . Scopula (pl. Scopulae ): compound organelle, structure or area, at the aboral pole of sessiline peritrichs especially; often cup-shaped with a thickened peripheral border or lip comprised of scopulary organelles, such as a plaque or field of kinetosomes , typically equipped with very short and immobile cilia, and pellicular pores ; may function directly as a holdfast organelle or, more commonly, may be involved in secretion or elabo- ration of a peduncle or stalk ; see Scopuloid (Sa, Fig. 2.11B). Scopulary Ciliature : see Scopulary Organelles . Scopulary Kinetosomes : see Scopulary Organelles . Scopulary Organelles : basically the kinetosomes of the scopula , although their clavate cilia , when present, may be included in the definition as well as the associated pellicular pores ; various addi- tional fibrillar and microtubular structures are associated with these scopulary kinetosomes, and presumably they are also involved in assembly of stalk components, when one is present. Scopuloid : organelle found at the posterior pole of the body of most suctorians ; comprised mainly of some kind of pellicular pores , which are presuma- bly involved in assembly of the sometimes lengthy, complex, non-living, never contractile stalk charac- teristic of suctorians (Sd, Fig. 2.11Cb, 2.11Cc). Scutica (pl. Scuticae ): transient “compound” kineto- somal structure or organelle of scuticociliates ; identifiable by its shape, location, and presence at a late ontogenetic stage during stomatogenesis ; quite conspicuous but generally non-ciliated at the time Glossary 51 of its existence, the scutica represents the remainder of an often much larger stomatogenic field of kineto- somes located near and slightly to the right of the posterior termination of the presumptive infra- ciliary base of the paroral in both the proter and opisthe; typically, manifests a hook-like or whip- lash configuration (giving it its name), recurving back to the right; presumably its kinetosomes have arisen from parts of the buccal infraciliature of the parental form ; its typical ultimate fate, if it does not disappear altogether or become entirely incor- porated into the paroral, is to persist as a ciliferous or non-ciliferous scutico-vestige of varying size and shape, in close juxtaposition to the base of the paroral and/or at the anterior end of the director- meridian ; the scutica is thought to be limited to members of its namesake, the scuticociliates , but its homologue may be present in species of other taxa; erroneously spelled scuticus (Sc, Figs. 2.4P, 2.7i, 2.11Df). Scuticobuccokinetal : buccokinetal stomatogenesis in which the opisthe ’s oral anlage derives either from the paroral and the scutica or solely from the paroral; found in scuticociliates (Fig. 2.11Df). Scutico-field : often used with reference to the slightly earlier multi-kinetosomal anlage stage of the scutica . Scutico-hook : term emphasizing what is the most typical appearance of the scutica , its hook-like configuration. Scutico-kinetosomes : kinetosomes comprising the scutica . Scutico-vestige : structure visibly remaining in the proter and opisthe after the identifiable stage of the dynamic scutica has passed; residual field of recognizable scutico-kinetosomes . Scuticus : a misspelling of scutica . Secant System: various lines of convergence of kineties in the somatic region ; pre- and postoral sutures and the convergence at the antapical pole are typical representatives of such systems; suture lines may also occur consistently elsewhere, espe- cially in heavily ciliated organisms that do not have simple bipolar kineties ; particularly striking in thigmotrichs , astomes , and clevelandellid arm- phoreans where such stabilized boundary lines or aires sécantes are of considerable taxonomic utility; non-preferred synonym is kinetal suture system (SS, Figs. 2.3, 2.7d). Sedentary : permanently attached to the substrate, which can be sediment, alga, another organism, or even the inside of a lorica ; see Sessile . Seizing Organ : a special, structured, discrete organelle associated with the proboscis of Didinium ; now known to be a bundle of discharged toxicysts and pexicysts used by Didinium in feeding. Secondary Meridian : see Ciliary Meridian (2CM, Fig. 2.7e). Secretory Organelle : used in a broader, more generalized way to refer to any vesicles, glands, pores, adhesive structures, and the like if they are involved in some form of secretion; see Ampulla, Secretory . Selfing : see Intraclonal Conjugation . SEM : scanning electron microscopy. Seme : unit of phylogenetic information; a unit character, either ancestral or derived, of high information content, usable in reference to any structural part or function of an organism, from the molecular level up to large and complex unit organelles or organellar systems . Semi-autonomous : now discarded term for a mode of stomatogenesis ; see Buccokinetal . Semi-membrane : formerly used as a synonym of the undulating membrane ; see Extensor Membrane . Sensory Bristle : rather widely applied term to many bristles or setae , even when the exact function is unknown; particularly used to describe both (1) the several short rows of clavate cilia in such hap- torians as Didinium and (2) the non-homologous, very short, non-motile cilia occurring in several longitudinal rows of pits on the dorsal surface of many hypotrichs and stichotrichs ; also called dorsal bristles ; the Tastcilien of older literature (SB, Figs. 2.3Ae, 2.7l). Sensory Organelle : generalized term probably often improperly or imprecisely applied to a vari- ety of structures found in ciliates that may or may not actually possess a sensory function; frequently implicated organelles include diverse bristles and setae , the brosse , other specialized cilia (e.g., caudal cilia , clavate cilia