D I K 



[ 75] 



D I P 



DIKE. (Sax.) 



1. A ditch ; a channel to receive water. 



2. A mound ; defence ; wall; fortification. 



3. Geologists use the word dike to express 

 a wall of mineral matter, cutting through 

 strata in nearly a vertical direction. 

 Lyell observes, " That it is not easy to 

 draw the line between dikes and veins ; 

 the former are generally of larger dimen- 

 sions, and have their sides parallel for 

 considerable distances ; while veins have 

 generally many ramifications, and these 

 often thin away into slender threads." 



DILU'VIAL. (dihivialis, Lat.) Relating 

 to the deluge. A term introduced by 

 Professor Buckland to distinguish accu- 

 mulations consequent on the deluge. 

 "It is always," says Dr. Mantell, "in 

 diluvial beds spread over the surface of 

 plains, or accumulated in the bottoms of 

 valleys, that the teeth and bones of mam- 

 malia have been discovered in various 

 parts of England." 



DILU'VIALIST. One who attributes cer- 

 tain effects, denied by others, as conse- 

 quent on the Noachian deluge. 



DILU'VIAN. (Lat.) A name applied by 

 Professor Buckland to the superficial beds 

 of gravel, clay, and sand which he consi- 

 ders to have been produced by the No- 

 achian deluge : loose and water-worn 

 strata not at all consolidated, and depo- 

 sited by an inundation of water. 



DI'NGLE. A dale ; a narrow valley between 

 hills ; a hollow. 



DINOTHE'RIUM. (from <5Tvo, and 6ij- 

 piov, Gr.) An extinct genus of terres- 

 trial mammalia. There are two known 

 species of dinotherium. The dinotherium 

 may be considered to have been the 

 largest of terrestrial mammalia. The 

 most abundant fossil remains of this 

 genus have been found at Epplesheim, in 

 Germany. In various parts of the south 

 of France, large molar teeth and osseous 

 fragments of dinotheria have been found 

 occasionally, and these were referred by 

 Cuvier to a gigantic species of tapir, and 

 named by him Tapir giganteus. 



Subsequent discoveries have enabled 

 Prof. Kaup to place the dinotherium in a 

 new genus, and to establish the fact that 

 it was an herbivorous aquatic animal, in- 

 habiting marshes and lakes, and that it 

 sometimes attained the length of eighteen 

 feet. The dinotherium holds an inter- 

 mediate place between the tapir and the 

 mastodon, supplying a link between the 

 cetacea and pachydermata. The scapula, 

 or shoulder-blade, is the most remarkable 

 bone hitherto discovered, belonging to 

 this animal ; it resembles that of the 

 mole, and seems to indicate that the fore- 

 leg was adapted for digging up the earth. 

 It appears also certain that this huge 



creature was furnished with a proboscis. 

 The dinotherium may be found figured in 

 Prof. Buckland's Bridgewater Treatise, 

 and in Mantell's Wonders of Geology, 

 from which works much of the preceding 

 account has been extracted. The dino- 

 therium is referrible to the miocene 

 period. 



DI'ODON. In Cuvier's arrangement, a genus 

 of fishes belonging to the family Gymno- 

 dontes, and thus named in consequence of 

 their jaws being undivided, and forming 

 one piece only above and one below. 

 Their skin is in all parts so armed with 

 spines, that they resemble the case of the 

 fruit of the horse-chesnut. Teeth sup- 

 posed to belong to diodon histrix have 

 been found in the chalk. 



DIO/CIA. (from t>i and ol/coc, Gr.) The 

 twenty-second class of plants in Lin- 

 nseus's artificial system. The stamens 

 and pistils are in separate flowers, and 

 situated on two separate plants. The 

 orders in this class depend on the cir- 

 cumstances of their male flowers. 



Diffi'cious. Belonging to the class Dicecia ; 

 plants which have the barren and fertile 

 flowers growing from the two separate 

 roots. 



DIO'PSIDE. (from Sio^iQ, Gr. transpectus.) 

 A mineral known also as alalite, baikalite, 

 and musite. It is a white or pale green 

 variety of augite. It occurs massive, dis- 

 seminated, and crystallized. It is found, 

 generally imbedded in Serpentine, in 

 Piedmont. It consists of more than half 

 silica, one fourth lime, about eighteen 

 per cent, magnesia, with a trace of alu- 

 mina and protoxide of iron. 



DIO'PTASE. The Cuivre Dioptase of Haiiy. 

 Emerald copper-ore, a very rare mineral 

 of an emerald-green colour, consisting of 

 oxide of copper and silica in nearly equal 

 proportions, with about eleven per cent, 

 of water. 



DI'ORITE. A variety of greenstone. 



DIORI'TIC. Resembling diorite ; contain- 

 ing diorite ; of the nature of diorite. 



DIP. To incline downwards ; to sink ; to 

 immerge. 



DIP. In geology, the downward inclina- 

 tion of strata. The point of the com- 

 pass towards which strata incline is called 

 their dip, and the angle of such inclina- 

 tion with the horizon is termed the dip, 

 or angle, of inclination. It sometimes 

 happens that a stratum, without varying 

 its direction, may be so bent as to dip two 

 ways in the same mountain, like the 

 sloping sides of the roof of a house, or 

 the letter V reversed A 



DIPE'TALOUS. (from dig and TrsraXoi/, 

 Gr.) Having two flower-leaves or petals. 



DI'PTERA. (from SIQ and Trrtpbv, Gr.) 

 The sixth order of insects in the Lin- 



