319 



LARK. 



LARYNX. 



350 



Thalaasidroma Bvlwerii, Bulwer's PetreL 



T. Wiltcmii, Wilson's PetreL 



T Leachii, the Forked-Tailed Petrel. 



T. jxlagica, the Storm Petrel. [TuALASSLDROHA.] 



LARK. [ALAUDA.] 



LARKSPUR. [DELPHINIUM.] 



LA'KUIIhK, a family of Hymenopterous Insects of the section 

 Fotore, distinguished by the labrum being either entirely or partially 

 concealed, and the mandibles deeply notched on the inner side near 

 the base. It contains the following genera : 1. Palarus (Lat.), in 

 which the antennae are very short, and are gradually thicker towards 

 the apex : the eyes are closely approximated posteriorly, and inclose the 

 ocelli : the second cubital cell is petiolated. 2. Tachytes (Panzer), 

 antenna! filiform, the basal joint slightly incrassated, the rest cylin- 

 drical ; superior wings with one marginal cell, slightly petiolated 

 and three submarginal cells, the third narrow and oblique ; mandibles 

 with a dentate process on the inner side near the base. T. pompili- 

 formii is about 24 lines in length; black, with the basal segments of 

 the abdomen red. It is not an uncommon insect in various parts of 

 England. 3. Larra : this genus differs from Tachytei (which is Lyrops 

 of Illiger) in having no tooth on the inner side of the mandibles at 

 the bue ; the eyes not being approximated posteriorly, and the meta- 

 thorax and abdomen being decidedly larger. 4. Z>inetus : eyes 

 converging posteriorly ; antennas filiform in the female, with the first 

 joint incrassate, hi the male larger, with a deep lateral impression, 

 the four following joints submoniliform, and the five next slightly 

 compressed and convoluted, the remaining three filiform; superior 

 wings, with one appendiculated marginal cell, and three submarginal 

 cells. But one species of this genus has been found in England. 

 5. Afitcophui (Jurine) has one marginal cell, which is not petiolated, 

 to the superior wing, and two submarginal cells, the second being 

 petiolated ; the antenna; are filiform in both sexes. There is but a 

 slight projection at the base of the mandibles. M. bicolor (Junine) 

 is the only species found in England, where it is apparently rare. 

 (Shuckard, Emay on the Indiyenoia Fossorial Hymenoptera.) 



LARVA, a term applied to that state in which an insect exists 

 immediately after its exclusion from the egg, and which precedes the 

 pupa state. The animals commonly called Grubs, Maggots, and 

 Caterpillars are larvte. Qrub appears to be a general term analogous 

 to larva ; the term Maggot is most generally applied to the larva state 

 of Dipterous Insects ; and Caterpillar, in the most common accep- 

 tation of the term, is used to designate the larva state of Lepidopterous 

 Insects. These three terms however are used in a very vague 

 manner. 



The most striking difference perhaps which exists between the 

 larva and the perfect insect consists in the superior powers of locomo- 

 tion and consequently better developed skeleton possessed by the latter. 



Though larva: never possess winga^ they vary much as regards the 

 development of the locomotive organs, and as these are more or less 

 perfect, so do the larvse resemble or recede from the insect in its 

 imago state. Hence Messrs. Kirby and Spence divide larva; into two 

 sections : those which, hi general form, more or less resemble the 

 perfect insect; and those which are unlike the perfect insect. The 

 larv;e of both sections moult, or cast their skin, several times during 

 their progress to maturity ; the number of moults varies according to 

 the species, and the period intervening between the moults depends 

 upon the length of the insect's existence in the larva state. In 

 these moults, not only is the whole external covering of the insect 

 cast, but even the lining of the intestinal canal and of the tubes of 

 the tracheae is shed. 



The greater portion of the larva) of the orders rthoptera, Ifemi- 

 ptera, and Jfomoptera, excepting that they have no wings, bear a 

 considerable resemblance to the perfect insect, and hence belong to 

 the first of the sections just mentioned. As however the muscles 

 which serve to support and give motion to the wings are attached to 

 the skeleton of the thorax, so, as might be expected, we find this part 

 in the perfect insect more unlike that of the larva perhaps than any 

 other; and again where (as in the imago state of Scutellera) a 

 portion of the thorax is greatly produced behind and serves to protect 

 the wings when folded, the larva, having no wings, does not possess 

 this peculiarity. 



Belonging to the second division, in which the larva does not 

 resemble the perfect insect, are the orders ffymenoptera, Coleoptera, 

 Newroptera, Lejridoptera, and Diptera. 



The larva) of Hymenopterous Insects are usually of a short ovate 

 form, and short and fleshy substance, devoid of legs or distinct head, 

 and the body lies in a bent position. In the Tenthredinetce (Latreille) 

 however we have a remarkable exception, the larva; of these insects 

 not only being furnished with six legs attached to the thoracic seg- 

 ments, but also possessing a great number of prolegs. These prolegs 

 are ugjally sixteen in number, and attached in pairs to the abdominal 

 segments ; in some there are but fourteen, and in others only twelve 

 prolegs. The larva; of the Tenthredinetce very much resemble those of 

 Lepidopterous Insects, but differ in the greater number of their 

 prolegs ; the head is large, rounded, flattened in front, and vertical in 

 position ; the body is always bent under, and when touched they roll 

 themselves up like the Mi. In the genus Pamphiliva (Lat.), the larva 

 I six thoracic legs, but no prolegs. 



The larvae of the Ooleoptcra are most commonly of an elongate, 

 cylindrical, or slightly depressed form ; the thoracic segments are 

 almost always provided with six legs, and there are seldom any pro- 

 legs on the abdominal segments. The head is furnished with mandibles, 

 maxilla;, labrum, labium, and antenna;, and very frequently with 

 ocelli. The parts of the mouth and the antenna; however do not 

 resemble those of the perfect insect. The antenna; are usually very 

 small, and composed of but three or four distinct joints. The ocelli 

 of the larva are replaced by compound eyes in the perfect insect. The 

 thoracic segments are often protected by a horny plate on the upper 

 surface : the prothorax, which is usually the largest, is generally so 

 protected. The legs, of which these segments have each a pair, are of 

 moderate size in most larva! of this order, and composed of a coxa, 

 trochanta, tibia, and tarsus ; the last however appears to be repre- 

 sented by a small jointlesa claw. The body is often soft, but some- 

 times, like the thorax, protected by horny plates, as in some of the 

 Carabid<e, SUphidie, &c. In the Cardbidce, Staphylinida;, and indeed 

 many families, it is somewhat depressed. In many of the Hetero- 

 merous Insects it is cylindrical, of a coriaceous texture throughout, 

 and the terminal segment is often furnished with horny appendages 

 at the apex, and one or two prolegs beneath. The larva; of many of 

 the Elttterides are also of a coriaceous texture and cylindrical form, 

 and the terminal segment of the abdomen is generally furnished with 

 horny appendages. These appendages are indeed very commonly 

 met with in Coleopterous larva;. In those species belonging to the 

 sections Lamdlicornes, Bltyncophora, and Longicornes, however, we 

 have not met with them, and the body is always of a soft and fleshy 

 texture. The larva; of the two last-mentioned sections have extremely 

 minute legs. 



In the order Neuroptera the larva) very much resemble in general 

 appearance many of those of the order Coleoptera : they always possess 

 six thoracic legs, but seldom any prolegs. In the Case- Worms (Tricho- 

 ptera) and some others there are a pair of prolegs attached to a terminal 

 segment of the abdomen. 



In the order Lepidoptera the larva; (or caterpillars) are soft and 

 fleshy, and usually of a cylindrical form. They possess 6 thoracic 

 legs and generally ten prolegs. The prolegs vary in number, and are 

 attached in pairs to the under side of the abdominal segments ; but 

 none are ever found on the 4th, 5th, 10th, or llth segments. In the 

 larva; of the Qeomelrce there are but four prolegs, two of which are 

 attached to the anal segment, and the other two to the ninth. Some of 

 the Tinnce have but two prolegs, and these are anal. In the genus 

 Apoda (Haworth) the larva; have no distinct prolegs, but in their 

 stead a number of small transparent shining tubercles, without claws. 

 " The prolegs of almost all lepidopterous larva; are furnished with a 

 set of minute, slender, horny hooks, crotchets, or claws of different 

 lengths, somewhat resembling fish-hooks, which either partially or 

 wholly surround the apex like a palisade. By means of these claws, 

 of which there are from 40 to 60 in each proleg, a short and a long 

 one arranged alternately, the insect is enabled to cling to smooth 

 surfaces, to grasp the smallest twigs to which the legs could not 

 possibly adhere ; a circumstance which the flexible nature of the 

 prolegs greatly facilitates." " When the sole of the foot is open, the 

 claws with which it is more or less surrounded are turned iuv. arils, 

 and are in a situation to lay hold of any surface; but when the 

 animal wishes to let go its hold it begins to draw in the skin of the 

 sole, and in proportion as this is retracted the claws turn their 

 points outwards, so as not to impede its motion." (Kirby and Spence.) 



The larva) of Dipterous Insects are for the most part soft and 

 fleshy, and without legs ; none have true jointed legs : some however 

 have prolegs. The head is usually soft and indistinct, but in certain 

 species the head is somewhat corneous, and of a determinate shape. 

 [INSECTS.] 



LARVA'RIA, the name of a group of Tertiary Fossils, proposed 

 by M. Defrance. (Blainville, Actinoloyie, p. 442.) 



LARYNX is the organ of the voice ; its framework is composed of 

 five cartilages, which are capable of being moved on each other in 

 various directions by muscles, so as to act upon two elastic bauds, on 

 which the voice essentially depends, and which are called the vocal 

 ligaments. 



The first, the Thyroid Cartilage (fig. 1), consists of two plates (a, b) 

 of dense tough fibro-cartilaginous substance, of an irregularly quadri- 

 lateral form, which are united at the lower part of their anterior edges 

 (c, c) at an angle of about 60, The prominence of this angular union is 

 felt in the front of the throat, forming what is called the Pomum Adami, 

 at the sides of and behind which the form of the cartilage may be 

 easily traced out with the fingers. The posterior edge of each plate 

 bears at each angle a process or horn (d, d, e, e), by which the thyroid 

 cartilage is attached by ligaments above to the hyoid bone, and below 

 to the cricoid cartilage. 



The Cricoid Cartilage (fig. 2) has somewhat the form of a signet ring. 

 It is inclosed within the angle of the thyroid cartilage, beneath whose 

 lower edge the front and narrowest portion (a) of its ring may bo felt, 

 with an interval of about a quarter of an inch between them. It has 

 an articulating surface on each side, by which it is moveably connected 

 with the inferior horns of the thyroid cartilage; and two other smooth 

 convex surfaces (b, b) on its upper and posterior edge, by which it is 

 articulated with the two arytenoid cartilages. 



