U M B 



[449 ] 



UNI 



UMBI'LICATED. (umlilicatus, Lat.) In 

 conchology, a term applied to such 

 shells as have a depression in the 

 centre, like a navel. Univalves 

 that have the umbilicus covered in 

 a greater or less degree by a thin 

 process, are termed sub-umbili- 

 cated. 



UMBILI'CUS. (umbilicus, Lat.) The 

 navel. In conchology, a circular 

 perforation in the base of the lower 

 whorl, or body, of many spiral 

 univalves, and common to most of 

 the Trochi, in some of which it 

 runs from the base to the apex. 



U'MBO. (umlo, Lat.) A boss or pro- 

 tuberance. In conchology, that 

 point of a bivalve shell situated 

 immediately above the hinge. This 

 word makes umbones in the plural. 



U'MBONATED. Bossed ; knobbed in the 

 centre. 



UNCONFO'RMABLE. In geology, a term 

 applied to a stratum or strata lying 

 in a different plane from the sub- 

 jacent strata upon which they rest. 

 Strata not lying parallel with those 

 beneath them. Supposing certain 

 strata to have been upheaved, so 

 that their inclination is at an angle 

 with the horizon, or even vertical, 

 such strata may all be, notwith- 

 standing, conformable one with 

 another; if, however, upon these 

 tilted strata, fresh strata be depo- 

 sited, the more recent strata lying 

 horizontally upon the subjacent 

 vertical or inclined strata, then the 

 superjacent strata are termed un- 

 conformable. 



UNCONFO'RMABLY. Not being in the 

 same plane with those upon which 

 they are deposited. Strata lie 

 unconformably when placed upon 

 others having a different line of 

 direction or inclination. 



U'NCTUOUS. (unctus, Lat.) Greasy; 

 soapy to the touch. In mineralogy 

 certain minerals are said to be 

 unctuous ; soap-stone is a good 

 example. 



UNCTUO'SITY. Greasiness. A character 



belonging to certain minerals, 

 which is very useful in assisting to 

 distinguish them. Some minerals, 

 when the finger is passed over their 

 surface, or their powder is rubbed 

 between the finger and thumb, feel 

 as if they were coated with some 

 greasy matter. The sensation is 

 different from that produced by 

 mere smoothness of surface. 



UNDERLIE. A term used in mining, 

 or by miners. In speaking of the 

 inclination of a fault it is better, 

 says Jukes, not to use the term 

 "dip" as if it were a bed, but to 

 adopt that of "hade," or "un- 

 derlie." 



U'NGUAL. (from unguis, a nail or 

 claw, Lat.) A name applied to 

 such bones of the feet as have 

 attached to them a nail, claw, or 

 hoof. 



U'NGUICAL. The name given to the 

 claw-bone of certain animals. 



UNGUI'CULATED. Clawed; possessing 

 claws. 



U'NGTTLATE. (from ungula, a hoof, 

 Lat.) Shaped like the hoof of a 

 horse. 



U'NGULITE GRIT. A member of the 

 Eussian Lower Silurian rocks, and 

 so named from a peculiar fossil it 

 contains: it is a white or ferru- 

 ginous sandstone, not much ex- 

 ceeding 100 feet in tfiickness. 



UNICA'PSULAR. (from unus, one, and 

 capsula, a capsule, Lat.) Having 

 one capsule only to each flower. 



UNILO'CTJLAR. (from unus, one, and 

 loculus, a cell or partition. ) Having 

 one chamber or cell only. In con- 

 chology, applied to shells which 

 are not divided by septa into cham- 

 bers. In botany, applied to seed 

 vessels not separated into cells. 



U'NIO. (unio, Lat. a pearl.) A genus 

 of freshwater bivalve shells, placed 

 by Lamarck in the family Nayades, 

 and by Cuvier in the family Myti- 

 lacea. Uniones are equivalve, in- 

 equilateral, transverse, internally 

 pearly, externally covered with an 



2 M 



