ETHUSA. 



EUCALYPTUS. 



620 



tion at the present day, we might establish a species for each individual. 

 He notices M. Hang's judicious observation, that in the same species 

 there are individuals armed with spines, and others devoid of those 

 appendages, and that the shades of this character are so gradual that 

 it is impossible to regard it as of the smallest importance. In follow- 

 ing out this principle, M. Rang considers . tubifera of Sowerby and 

 . Cailliaudi of Fdrussac as identical, and E. Corteroni of Michelin 

 to be the same as E. plumbea of Fdrussac. It is to the last-named 

 species that M. Deshayes thinks that the genus Mulleria should be 

 referred. 



Etheria, or, as some write it, jElheriti, has not yet been discovered 

 in a fossil state. It should be remembered that Rafinesque uses 

 the term for a genus of Macrourous Crustaceans belonging to the 

 Paitvmonidce. 



ETHU'SA, a genus of Brachyurous Crustaceans (tribe Dorippians), 

 established by M. Roux at the expense of the genus Dorippe of 

 Fabricius and other naturalists. 



M. Milne-Edwards observes that this genus is easily distin- 

 guished from Dorippe by the conformation of the apertures 

 leading to the respiratory cavity, which here present the normal 

 disposition. 



Carapace nearly quadrilateral, but rather longer than it is wide, 

 and very much flattened ; front large, orbits directed forwards, very 

 incomplete ; eyes carried on a rather long and very projecting peduncle ; 

 they pass beyond the external angle of the carapace, and are not 

 retractile. The internal antenna; are bent back (se reploient) forwards, 

 in fossettes placed under the front ; the external antenna; are rather 

 long ; their first joint is cylindrical, and separates the antennary fos- 

 sette from the orbit ; the third is longer than the second. The buccal 

 frame (cadre buccal) is triangular, and reaches to the border of the 

 antennary fossettes ; the jaw-feet are much shorter, and leave naked 

 the anterior portion of the jaw-feet of the first pair, which complete 

 forwards the canal of the respiratory cavity ; the third joint of the 

 external jaw-feet is shorter than the second, nearly oval, sharply trun- 

 cated forwards, and articulated with the following joint by the middle 

 of its anterior border. The Pterygostomian regions are nearly quad- 

 rilateral, and are not prolonged between the base of the external jaw- 

 foot and of the first thoracic foot, as in the Dorippes. The sternal 

 plastron is oval. The anterior feet are short and slender in both 

 sexes ; in bending they form a double elbow, as in Homola. The 

 succeeding feet are long, especially those of the third pair ; those of 

 the fourth pair are, on the contrary, extremely short, and inserted 

 below the preceding ; finally, the posterior feet, longer than the fourth 

 pair, are inserted above and in front of them, and, like them, are 

 terminated by a very short, hooked, and subcheliform tarsus. The 

 abdomen in the male has seven distinct joints ; in the female it has 

 only five : the first two rings are directed backwards and on the same 

 plane with the carapace. 



Ex. K. Maocarone (Roux), Cancer Matcaront (Herbst). 



Elhvna Slatcaronf. 



ETI'SUS, a genus of Brachyurous Crustaceans (Cancerians of M. 

 Milne-Edwards). 



Carapace less oval and wide than in most of the Arched Cancerians 

 (Cance'rie'ns ArqucSs). The front is large, lamellar, and divided on the 

 mesial line by a fissure, as in the Xanthi ; but the two large and 

 truncated lobes which form the principal part are separated by a deep 

 notch of the anterior and superior angle of the orbit, which is rounded 

 an^ projecting ; the latercr-anterior borders of the carapace are strongly 

 toothed. The internal antenna: are bent back nearly longitudinally, 

 and the basilary joint of the external antennae, which is very large, 

 unites with the front, and presents on the external side a prolonga- 

 tion which fills the hiatus of the internal orbital angle ; finally, the 

 moveable stem of these antennae, which is very short, is inserted com- 

 pletely out of this hiatus, below the front and nearer to the antennary 

 fotwette than to the orbit. The external jaw-feet present nothing 

 remarkable ; the feet of the first pair are rather large, and the chelic, 

 which are much enlarged and rounded at the end, are deeply hollowed 

 into a spoon-shape. 



M. Milne-Edwards, who gives the above description, divides this 

 small group, which he considers as forming the passage between the 

 Xanthi and J'latycarcini, into the two following sections : 



WAT. HIST. DIV. vot. ii. 



a. Carapace scarcely knobbed above. 



Ex. E. denlatiis. Length three or four inches; colour reddish. 

 Locality, the Indiau Archipelago. 



Etisus dentattu. 

 0. Carapace covered with knobs, separated by deep furrows. 



Ex. E. unaylyptiis. Length about an inch and a half; colour 

 whitish (?). Locality, Australia. 



EUASTRUM. [DESMIDEA] 



EUCALY'PTUS, a genus of Australian Plants, consisting of lofty 

 trees, with a volatile aromatic oily secretion in their leaves, and 

 a large quantity of astringent resinous matter in their bark. They 

 belong to the alternate-leaved division of Myrtacefe, and are generi- 

 cally known among these plants by their corolla being absent, and the 

 limb of their calyx consolidated into a hemispherical or conical cap, 

 whtch is thrown off when the stamens expand. 



This genus occurs in the Malayan Archipelago, but is chie8y Aus- 

 tralian, and, together with the leafless Acacias, gives a most remarkable 

 character to the scenery. The species exist in great profusion, and 

 form the largest trees in the forests of that part of the world. A 

 modern writer upon the plants of Van Diemen's Laud says that 

 Eucalypttts seems as if it had taken undisturbed possession of those 

 Australian regions, clothing as it does with a stupendous mantle the 

 surface both of Van Diemen's Land and Australia ; while the inter- 

 mixture of other plants which this lordly tribe permits is, compared 

 with its own great extent, but small and partial. Wherever you go, 

 one species or other is constantly before you. 



No trees in the world so constantly or rapidly arrive at gigantic 

 dimensions : they often become hollow, and are then used by the 

 traveller as roomy places of shelter at night. Frazer found a hollow 

 Eucalyptus at Moreton Bay, used by the natives as a cemetery. Even 

 at Swan River, where, according to the report of Frazer, the species 

 are stunted, they also attain a huge size. E. culophylla, attains a 

 height of 150 feet, and a girth of from 25 to 50 feet is not an uncommon 

 dimension of these trees. Their timber is represented as highly 

 useful for domestic and other purposes ; being so soft at first as to 

 render the felling, splitting, and sawing up of the tree, when green, a 

 very easy process, and when thoroughly dry becoming as hard as oak. 



. retinifera has leaves with very minute and numerous little dots, 

 ovate-lanceolate, with long tapering points narrowed to the base, 

 with a vein next the margin. The flowers are umbellate, on a com- 

 pressed peduncle rather longer than the petiole. The lid is conical, 

 taper, leathery, twice as long as the capsule. The bark is so extremely 

 astringent as to yield a gum not inferior to Kino, and sold as such. 

 The bark of this and other species is so hard as to cause them to be 

 called Iron-Bark Trees by the colonists. The Blue Gum-Tree and some 

 others have the singular property of throwing it off in white or gray 

 longitudinal strips or ribands, which, hanging down from the branches, 

 have a singular effect in the woods. 



In many species the leaves are so variable in their form and other 

 characters at different ages of the tree, or in different situations, that 

 it is a matter of difficulty to know how they are to be botanically 

 distinguished from each other ; and in fact the subject of the distinc- 

 tion of species has hardly yet been taken up, no botanist feeling com- 

 petent to undertake the task without some personal acquaintance with 

 the plants in a native state. The leaves, instead of presenting one of 

 their surfaces to the sky and the other to the earth, as is the case 

 with the trees of Europe, are often arranged with their faces vertical, 

 so that each side is equally exposed to the light. 



. robutta contains large cavities in its stem between the annual 

 concentric circles of wood, filled with a most beautiful red or rich 

 vermilion-coloured gum, which flows out as soon as the saw affords 

 an opening. 



E. mannifera, exudes a saccharine mucous substance resembling 

 manna in its action and appearance, but less nauseous. It is not pro- 

 duced by insects, and only appears in the dry season. Other species 

 yield a similar secretion at Moretou Bay and in Van Diemen's Land. 

 Mr. Backhouse says it coagulates, and drops from the leaves in 

 particles often as large as an almond. 



s 



