GLOSSARY. 



853 



Sundance — upper Jurassic of the Black 

 Hills, etc. 



Super — a prefix meaning over, above, 

 beyond. 



Superradial — in crinoids, see II., 489. 



Superior — higher in position. 



Supplementary — additional. 



Supra — a prefix, meaning over, beyond; 

 akin to super. 



Suture — the line of junction between 

 two parts. In crinoids, the line of 

 union between adjacent plates. In 

 gastropods, the external line of junc- 

 tion between two contiguous whorls. 

 In cephalopods, the line of junction 

 between wall of shell and septum, 

 seen on breaking away the former 

 (see II., 21, 22). In trilobites, the 

 dividing line between the fixed and 

 the free cheeks, commonly called 

 facial suture. 



Sweetland Creek shales — upper Devonic 

 of Iowa. 



Sylvan shale — lower Siluric of Okla- 

 homa, 



Sylvania sandstone — middle Monroan 

 of Michigan, Ohio, etc. 



Symmetry — the reversed repetition of 

 parts with reference to an axis. 

 Bilateral symmetry — the symmetrical 

 duplication of parts on each side of 

 a vertical axis, as in Crustacea. 

 Radial symmetry — the symmetrical 

 repetition of parts around a com- 

 mon vertical axis, as in Hydrozoa. 



SynapticulcB — in corals, the conical or 

 cylindrical transverse projections 

 from the sides of the septa ; those of 

 adjacent septa frequently become 

 united. 



Synonym — among fossils, see I., 6. 



Syrinx — in brachiopods, a shelly tube, 

 open along its inner margin and par- 

 tially enclosing the pedicle, devel- 

 oped in the delthyrium of some spire- 

 bearing forms, as in Syringothyris. 



Sysygy — in crinoids, see II., 490. 



Tabulce — the transverse continuous 

 floors which extend across the whole 



coral (see Figs. 80, upper, and no, 

 lower). 



Tabulate — in corals, referring io the 

 presence of the tabulae. 



Taconic — An American term equivalent 

 to the Cambric. 



Tallahatta — middle Eocenic of Ala- 

 bama. 



Tampa limestone — middle Oligocenic of 

 Florida. 



Tarsus — in insects, the foot (see II., 

 420). 



Taylor marl — middle Cretacic of Texas. 



Taxodont dentition — in pelecypods, the 

 arrangement of teeth to form a con- 

 tinuous row, as in Area (see I., 361). 



Teeth — articulating projections on the 

 margins of the valves of bivalve 

 shells. In brachiopods, the pair of 

 wedge-shaped projections bounding 

 the base of the delthyrium (see Fig. 

 301, i). In pelecypods, see lateral 

 and cardinal teeth. 



Tegmen — the vault or cover of the 

 calyx of crinoids (see Fig. 1805). 



Tegminal — referring to the tegmen 

 (see II., 492). 



Tegulce — see II., 424. 



Tehuacan limestone — lower Comanchic 

 of Mexico. 



Tejon — lower Eocenic of the Pacific 

 coast. 



Teleodont dentition — in pelecypods, see 

 I., 361. 



Telson — in the Merostomata, some of 

 the Trilobita and Phyllocarida, the 

 final segment of the abdomen ; it is 

 often sword-shaped (Fig. 1701). 



Tentacle — a more or less slender, flex- 

 ible process, used as an organ of touch 

 or for capturing prey (see Figs. 31, 

 56, 1230). 



Tenuous — thin, slender. 



Terebratuloid — like the genus Tere- 

 bratula (see L, 181, 3). 



Terete — cylindric and slightly tapering. 



Terga — in Balanus, the more vertical 

 of the two pairs of movable plates 

 which form the operculum. In in- 

 sects, see II., 420. 



