LOCOMOTION OF ANIMALS. 



LOCU8TA. 



5J1 



joint : the succeeding portions of the liuibs are linked together by 



hinge-joinU. The axe* of these joint* are turned at right angles to 



ach other, so that they have the power of executing increments in 



different plane*, some in a vertical, and others in a horizontal direction. 



When the perfect insect walks, it is observed to move three of its 



legs simultaneously, whilst the other 



Hj. 16. three remain on the ground, supporting 



\-* the body and urging it forwards. The 

 f feet which move simultaneously are the 



/ fore and hindermost feet on one side, 



/ and the middle foot on the opposite 



Hide ; consequently the whole of the nix 

 feet are moved to accomplish two steps. 

 In the first movement the legs 1, 2', 3 

 (fy. 46) remain on the ground, whilst 

 those marked 1', 2, 3' are raised and 

 advanced, to take a new position on the 

 plane of support : afterwards, whilst 

 the legs 1', 2, 3' support the body in 

 a similar manner to those which pre- 

 ceded them in that office, the legs 1, 2', 

 3 are raised, and again advanced ; and 

 by the alternate action of the six lees in the order just described, the 

 progression of tho insect when walking is accomplished. The extra- 

 ordinary power with which insect* are endowed of walking with perfect 

 ease and security up tho smooth polished surface of glass, and in an 

 inverted position on the ceilings of rooms, is found to depend on different 

 varieties of structure. The feet of the house-fly are found to be fur- 



Fig. 47. 



Fig. 48. 



nulled with two membranous suckers, as seen in fg. 47 ; and in the 

 Bitriofcbnlu there are three of these suckers, as shown infy. 48. These 

 tuckers are membranous sacs, which are acted on by numerous muscles, 

 so that when the foot is placed on n smooth surface the suckers become 

 enlarged by means of their muscles, and a vacuum is produced. The 

 pressure of the air without becomes by this means sufficient to keep the 

 foot firmly pressed on the surface to which it is applied. We here see 

 the reason why the house-fly chooses the smoothest surfaces of an apart- 

 ment to walk upon, unless it happens to be moving horizontally ; for 

 if the surfaces were rough, the vacuum under the feet would not be 

 perfect, and it would fall. In other instances the hairs are found 

 hooked, whilst some insects secrete a viscid substance, which causes 

 them to adhere to the objects on which they are placed. Many insects, 

 as the fly, are in the larva state destitute of legs, but even these con- 

 trive to drag themselves nlong by the alternate expansion and contraction 

 of their body. We are familiar with an instance of this kind of move- 

 ment in tho maggot commonly found in the hazel-nut. As soon as it 

 is out of the shell it strides along ; but, its trunk being cylindrical, it 

 frequently rolls over in it* course. Other larva;, not content with the 

 low piTigrsM made by the method above-mentioned, raise the central 

 portions of the body high above the plane of support, and by means 

 of alternately extending and contracting the body, take steps of con- 

 siderable length. This kind of movement is shown in ty. 49. The 



Fif. 49. 



trunk i first drawn forward from a to 4, ami the Vd is tlicn extended 

 from e to rf .- and thus at each step these larva; pass over a space equal 

 to a i or c <t I Miritii: thin process many larvas, such as the Geomdra, 

 i-pin a silken thread, the length of which is consequently tho measure 

 f ilirir progress made in walking. 



Leaping. -Man* insects, such as the flea, the grasshopper, and tin- 

 cricket, are capable nf performing extraordinary leaps compared with 

 their bulk. In all the leaping InsecU the binder legs greatly exceed 

 the rest in length and strength, and it Is in consequence of the length 



and power of this pair that insects are capable of projecting them- 

 selves to the great distances they are known to traverse. The legs are 

 first bent as much as possible, and then suddenly expanded with great 

 force, so as to propel the body through the air. As the grasshopper 

 resides amongst the long grass of meadows, such a mode of progres- 

 sion is requisite to enable it to pass over the rugged surfaces surrounding 

 it on all sides ; and we well know with what ease and unerring preci- 

 sion this little creature leaps from point to point. 



Worms. Amongst the A nnelidit, or Worms, we find a great diversity 

 of form, and of locomotive organs, suited to the habits and economy 

 of each animal. Some live entirely on land, others reside in water, 

 and are excellent swimmers. The Lumbi-ici, or Earth- Worms, being 

 those with which people generally are most familiar, will be selected 

 to give an idea of their mode of progression. The body of the earth- 

 worm ia cylindrical, and nearly of equal diameter from head to tail. 

 It is supported by numerous rings encircling the long axis of the 

 trunk throughout, and each ring is furnished with eight conical spines, 

 which are called into action when the animal walks. Between these 

 rings two sets of muscular fibres pass from ring to ring, one set of 

 muscles passing longitudinally, and the other set obliquely. By the aid 

 of these fibres the body of the animal can be either lengthened or 

 contracted, as also twisted in various directions. When touched, the 

 worm immediately assumes the form of the letter S. In walking it 

 expands one portion of the body, and contracts the next successively, 

 so that it requires a series of expansions and contractions throughout 

 its entire length to accomplish a single step. For this reason the 

 progress of the worm is very slow, not being capable of effecting more 

 than about the rate of 30 feet per hour. 



For a further account of the special movements of animals see 

 FLYING ; SWIMJIINO. 



[In this article we have had the advantage of using the greater 

 portion of an admirable series of articles which appeared in the 

 ' Penny Magazine,' and which were written by Mr. J. Bishop, F.R.S., 

 n gentleman eminent for his physiological attainments, and the author 

 of the profound and original article on ' Motion,' in the ' Cyclopaedia 

 of Anatomy and Physiology.'] 



LOCUST. [LOCTSTA.] 



LOCUST-TREE is the Bobinia Pteudacacia of botanists, a North 

 American forest-tree. [ROBINIA.] The same name has also been given 

 to the Ceratonia Siliqua, the Carob- or Algaroba-Tree, which is found 

 in the Levant, and bears large pods filled with nutritious pulp. 



LOCUSTA (Geoffrey ), a genus of Insecte belonging to the order Orthoi* 

 tera and the section ScUtatoria. The species of this genus have been 

 recently referred by English authors to the genus Gryllns. [On YLLID.E.] 

 The terms Locust and Grasshopper are applied to various insects of 

 the order Orlhoptera, and belong to a section of that order to which 

 Lutreille applied the name Saltatoria, on account of the power of 

 leaping which they possess. The insects belonging to this section are 

 remarkable for the great size of the thighs of the posterior pair of legs, 

 which are generally very long, and adapted for leaping. The males of 

 souie of the species make a shrill sound by the friction of the elytra. 

 The part by which the sound is created is situated on the inner side 

 and near the base of each elytra, is often transparent, and lias been 

 compared to a piece of talc. In other species the sound is produced 

 by the friction of the thighs against the elytra. 



The section Saltatoria contains three families, to which the names 

 AcheticUe, GryUida, and Locuttida are applied by Dr. Leach. The 

 family Ac/teltda is thus defined: Elytra horizontal; wings longitu- 

 dinally folded, often produced beyond the elytra; tarsi S-joiuted. 

 This family contains the genera (,'njllotalpa of Kay, Leach, and others, 

 of which the Mole-Cricket (<J. nUyarit) of this country affords an 

 example, and Acheta of Fabricius, which is the tii-ylltu proper of tho 

 ' Ilcgne Animal.' The Common Cricket in our houses (A ditto, donut- 

 tica) belongs to this genus. The genera Trittaclytnt nml .!////, - .<,/,/, <l< 

 arc also included in the present family. In the family GrgMda tin- 

 wings are disposed in an oblique manner when folded, the tarsi are 

 4-jointed, the antenna: are long and setaceous, and tho oviduct is 

 exerted in the friuale, of a long and compressed form, and recurved. 



Tho insects of this family form tho genus Loctuta of tho ' Kegno 

 Animal.' The Acrida (Gryllut, Lociuta) viridiuima, is the largest 

 among the British species of the present group. This insect is not 

 uncommon in Home parts of England, and is about two inches in 

 length, and of a bright green colour. [l!nYi,ui>..] 



The family Loctutida is distinguished by the following characters : 

 Wings when folded meeting at an angle ; tarsi 3-jointed ; antenna; 

 filiform or usiform ; oviduct not exserted. The tocutlida of Dr. 

 I-c.-K.-h are comprised in tho genus A cridinm by Latreille. Unfortu- 

 nately there is much confusion as regards the names of some of the 

 genera and sub-genera contained in this as well as the other families 

 above noticed. Names originally applied to large groups are restricted 

 to smaller flections, and as entomologists differ in opinion as to which 

 particular division shall retain the original name, the same names are 

 used to designate different groups; henco the references made to 

 Latreille's jrortion of the ' U6gne Animal.' 



Tin? principal genera contained in tho family Lociulidte are the 

 following : 



Loctula (Leach), in which the hinder legs arc about equal to tho 

 whole body in length, and the antennrc filiform or terminated in a 



