GLOSSARY. 



855 



Ttirriliticone — an asymmetrically coiled 



Ammonoid shell (see II., 19). 

 Turrit ellif or tn — shaped like Turritella ; 



spire slender, of many whorls (see 



Fig. 1064). 

 Type — an individual animal from which 



a recognizable description or figure 



has been prepared and upon which a 



specific name has been based. 



Co-type — each of the several speci- 

 mens from which a single species 

 has been described when no single 

 specimen has been indicated as 

 holotype ; called also syntype. 



Genotype — the one species upon 

 which a genus is founded. 



Holotype — the one specimen upon 

 which a species is founded. 



Type of genus — see genotype. 



Uffington shale — upper Allegheny (mid- 

 dle Carbonic) of West Virginia. 



Uintah group — upper Eocenic of Utah. 



Uintah quart site — basal Cambric (or 

 pre-Cambric) of Wasatch Mountains. 



Ulsterian series — a division of the mid- 

 dle Devonic. 



Ultimate — last. 



Umhilicated — provided with an um- 

 bilicus. ^ 



Umbilicus — an external depression or 

 opening at the center of many loosely 

 coiled shells. It is usually at the base 

 of gastropods and at the sides of 

 cephalopods (see Figs. 851, f, g, and 

 1405). 



Umbo — the area about and including 

 the beak in bivalve shells (see Fig. 

 218, u. In pelecypods, Fig. 476). 



Undulating — formed with elevations 

 and depressions, resembling waves. 



Undulation — a wave-like elevation. 



Uni — a prefix, meaning one. 



Unilocular — of one chamber. 



Uniserial — in one row or series. For 

 application in crinoids, see II., 490, 

 and Fig. 1806. 



Ute limestone — upper Cambric and 

 lower Ordovicic of Wasatch Moun- 

 tains. 



Utica shales — upper Ordovicic of Can- 

 ada, New York, Pennsylvania, etc. 



Valves — the one or more pieces of 

 which a shell consists. Brachiopods 

 and pelecypods are bivalve ; gastro- 

 pods and cephalopods are univalve. 



Valvular — pertaining to a valve. 



Vaqueros formation — lower Miocenic 

 of the Pacific coast. 



Varicose — irregularly enlarged. 



Varietal name — see variety. 



Variety — the last of the three names 

 (not the author's name) sometimes 

 applied to a single fossil. Most fos- 

 sils have but two names, the generic 

 and the specific. 



Varix (plural varices) — in gastropod 

 shells, a row of spines or a ridge, ex- 

 tending across each of the whorls, 

 denoting the former position of the 

 outer lip, as in Murex. In cephalo- 

 pods, see II., 22,- 



Vascular — pertaining to the tubes or 

 vessels for the circulation of plant or 

 animal fluids. 



Vascular sinuses or markings — im- 

 pressions upon the inside of brach' 

 iopod shells, indicating the pres- 

 ence in the living animal of folds 

 (pallial sinuses) in the mantle to 

 carry the primitive " blood " (see 

 Figs. 221, s, ps, o; 305, 309, v). 



Vaulted — arched. 



Veins — for arrangement in insects, see 

 II., 420, and Fig. 1724' 



Venter — the abdomen. In most cepha- 

 lopod shells, the exterior of the coil. 



Ventrad — toward the venter. 



Ventral — pertaining to the lower or 

 abdominal side or venter. 

 Ventral lobe — see siphonal lobe. 

 Ventral valve — in brachiopods, the 

 pedicle valve. 



Ventricose — very convex ; strongly 

 swollen. 



Ventrocentran — see Fig. 1231. 



Vermicular sandstone — upper Kinder- 

 hook of Mississippi Valley. 



