D I 



[ 139] 



DIP 



a proboscis, by means of which it 

 carried to its mouth the vegetable 

 food collected by its tusks and 

 claws. The dinotherium is refer- 

 rible to the miocene period. 



A very remarkable peculiarity of 

 formation in the dinotherium con- 

 sisted in the possession of two 

 immense tusks, which were curved 

 downwards, and resembled those 

 of the upper jaw of the walrus, 

 but in the dinotherium these tusks, 

 nearly four feet in length, were 

 placed at the anterior extremity of 

 the lower jaw. These tusks are 

 supposed to have served as instru- 

 ments for raking and grubbing up 

 by the roots large aquatic vegeta- 

 bles. It is also thought that these 

 tusks might have been used by the 

 animal for the purpose of hooking 

 itself, as it were, to the bank, and 

 thereby enabling it to keep its 

 head above water during sleep ; as 

 well as for means of defence. 

 DJL'ODOI*. In Cuvier's arrangement, 

 a genus of fishes belonging to the 

 family Gymnodontes, 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 supposed 

 to belong to diodon hisirix have 

 been found in the chalk. 



"One day," says Mr. Darwin, "I 

 was amused by watching the habits 

 of a Diodon which we caught. 

 This fish is well known to possess 

 the singular power of distending 

 itself into a nearly spherical form. 

 Cuvier doubts whether the Diodon 

 in this state is able to swim, but 

 not only can it thus move forward 

 in a straight line, but likewise it 

 can turn round to either side. 

 This Diodon possessed several means 

 of defence. It could give a severe 

 bite, and could eject water from 

 its mouth to some distance. By 



the inflation of its body, the 

 papillae, with which the skin is 

 covered, become erect and pointed. 

 But the most curious circumstance 

 was, that it emitted from the skin 

 of its belly, when handled, a most 

 beautiful carmine-red and fibrous 

 secretion, which stained ivory and 

 paper in so permanent a manner, 

 that the tint is retained with all its 

 brightness to the present day." 

 Mr. Darwin adds " I am quite 

 ignorant of the nature and use of 

 this secretion.'* 



DKE'CIA. (from Sis and OIKO*, Gr.) 

 The twenty-second class of plants 

 in Linna3iis's artificial system. The 

 stamens and pistils are in separate 

 flowers, and situated on two sepa- 

 rate plants. The orders in this 

 class depend on the circumstances 

 of their male flowers. 



DIO'PSIDE. (from diotyis, Gr. trans- 

 pectus, in reference to its trans- 

 parency.) 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 Ser- 

 pentine. It consists of more than, 

 half silica, lime, about eighteen 

 per cent, magnesia, with a trace of 

 alumina and protoxide of iron. 



The Abbe Haiiy states the prim- 

 itive crystal of Diopside to be an 

 acute rhomboidal prism. The mea- 

 surements of the angles by the 

 reflecting goniometer are 87 5' 

 and 92 55'. Diopside is con- 

 sidered by Haiiy to be a variety of 

 Pyroxene. 



DIO'PTASE. (The Cuivre Dioptase of 

 Haiiy.) Emerald copper -ore, a very 

 rare mineral of an emerald-green 

 colour, consisting of oxide of cop- 

 per and silica in nearly equal pro- 

 portions, with about eleven per 

 cent, of water. 



DI'ORITE. A variety of greenstone, 

 composed of hornblende and albite. 



DIP. In geology, the downward 



