358 



ORNUS ORTHOPTERA. 



feet, the dimensions of the female being inferior to 

 those of the male. The long silky fur on the body is 

 dark brown, the downy fur grey, and most abundant 

 on the under part of the animal. The tail is flat- 

 tened, has an up-and-down motion in swimming, 

 and is about one fourth of the length of the other 

 parts. 



ORNUS (Persoon). A genus of deciduous trees, 

 natives of Italy and North America, and commonly 

 known by the name of the flowering-ash. The 

 flowers are diandrous, and the genus ranks among 

 the Oleirue. These grow with us to be middle-sized 

 trees, and their tufts of flowers are rather showy. 

 They may be raised from seeds, but they are most 

 commonly increased by grafting upon ^the common 

 ash. 



OROBANCHEjE. A small natural order, con- 

 taining only two genera, viz., Lathraea and Orobanche, 

 of which there are seven species, six of the last and 

 one only of the former. They are mostly parasites, 

 living either upon dead or living plants. The Latk- 

 reza is found on the roots of trees in shady woods, 

 and provincially called tooth-wort, from the scales on 

 the stem resembling teeth. The Orobanche, minor 

 and major, are found growing on the roots of common 

 broom (Genista tinctoria), hence called broom-rape, 

 but much more frequently on the roots of the red or 

 broad clover, and in such quantity as to form one- 

 third of the second crop, being, however, a very 

 useless addition, as it is a robber of the clover as well 

 as the broom. The O. ramosa is a parasite on hemp. 

 They are leafless plants, having scales occupying 

 their place. 



OROBUS (Tournefort). A genus of perennial 

 herbs, mostly European. They bear pretty dia- 

 delphous flowers followed by pods, which places them 

 in the order LeguminoseE. They are called tfce bitter- 

 vetch, and several of them are cultivated as ornamental 

 plants. 



ORPIMENT. This valuable mineral is much 

 employed as a pigment. It was formerly better 

 known as ruby sulphur. The primitive figure of the 

 red orpiment is an oblique four-sided prism, and two 

 of its most common secondary figures are represented 

 in the annexed engraving. 



It occurs most frequently in veins in gneiss and 

 clay-slate, and it is usually accompanied with arsenic. 

 Yellow orpiment is of a lemon colour, and is rarely 

 found in the same situations as the preceding. It is 

 found in great beauty at Andreasburg in the Hartz 

 mountains. 



ORPINE is the English name of the Sedum tele- 

 phium of Linneeus, a British plant found in hedge 

 banks. The genus Telephium, a south of Europe 

 plant, is also called Orpine. 



ORTHOCERAS (Dr. R. Brown). A New Hol- 

 land genus, belonging to Orchidecs, introduced about 

 1826. It is a cold frame plant. 



ORTHOPOGON (Dr. R. Brown). A genus o 

 tropical Graminece, one of which, the 0. hirtellus, is 

 cultivated in the West Indies. 



ORTHOPTERA (Olivier). An order of man- 

 dibulated insects, united by Linnaeus at first with 

 the coleoptera, and afterwards arranged by him with 

 the haustellated hemiptera, from the construction of 

 the wings. By Geoffroy they were also arranged 

 with the coleoptera, forming the third primary divi- 

 sion of that order. 



De Geer, however, saw the impropriety of retain- 

 ing these insects in either of these two classes, from 

 each of which they differed in the structure of the 

 wings and mouth, or in the nature of their metamor- 

 phoses, and accordingly raised them to the rank of a 

 distinct order, to which Olivier subsequently gave 

 the name of Orthoptera, from the longitudinal or 

 straight (opQof) folding of the wings (wrtpa). Fabri- 

 cius had also raised these insects to the rank of an 

 order which he termed Ulonata, from the Greek 

 ouAof, an outer gum, and yvaOot, a jaw, the lower 

 jaws being laterally armed with a helmet-like plate, 

 which is in fact but the greatly developed external 

 lobe of the maxillae. See vol. ii. p. 853, fig. 104, c. 



The body in these insects is generally of a large 

 size, less firm in its consistence than in the cole- 

 optera, with the tegmina or wing-covers soft, coria- 

 ceous, provided with numerous nervures, and not 

 uniting when closed in a straight line down the back ; 

 the wings are membranaceous, and furnished with 

 equally numerous nerves, arranged longitudinally, 

 with transverse threads, so that the wings fold up 

 something like a fan ; the mouth is furnished with a 

 very considerably-developed organ, which is the 

 analogue of the tongue. These characters alone 

 would suffice to point out their differences from the 

 coleoptera, in which the outer lobe of the maxillae is 

 not helmet-like, and the wings are transversely folded, 

 whilst the mouth in the hemiptera, is not formed 

 for mastication, being unprovided with jaws, and the 

 wings are simple, extended, when at rest, beneath 

 the wing-covers, without being folded. 



The head of orthopterous insects is in general 

 large, and almost perpendicular in the majority, 

 the antennae being placed on its upper part, and 

 which are of variable length and structure, but often 

 long and multiarticulate ; the eyes are large and 

 lateral ; and the ocelli which are found in the majo- 

 rity are placed on the forehead, sometimes widely 

 apart ; the thorax, or, more strictly speaking, the 

 pronotum, is large, being in many species extended 

 considerably backwards ; the abdomen is long, gene- 

 rally of a conical form, and terminated in the females 

 of many species by an exserted apparatus for depo- 

 siting the eggs in the shape of a sword or cutlass. 



The legs of the Orthoptera are very long, and are 

 employed in giving considerable activity to these 

 insects, in some of which these organs are simply 

 organs fit for walking (Slatta) ; in others the fore 

 pair of legs become instruments for seizing their 

 prey (Mantis') ; whilst in the rest the hind legs are 

 greatly increased in size, supporting strong internal 

 muscles, enabling the insect to effect leaps of great 

 extent ; these legs are also employed in some species 

 to produce a loud chirping noise by their friction 

 against the base of the wing-covers (Locusta], which 

 noise appears to be the call of the males, by which 

 sex alone it is produced. We have already, in the 

 article GRASSHOFPEJR, given a more detailed account 



