ciniim undatum), it is recurved (fig. 759. A, 2). 



Fig. 759. 



1H2 TONGUE. 



among naturalists *; but since a certain oral species also, as in the common whelk (Buc- 

 appendage, at least in some of the orders, 

 has received by common consent the name 

 of lingua, I shall briefly describe it. The 

 mouth of insects is furnished with two lips 

 an upper lip, or labrum, and a lower lip 

 or lahium ; besides four jaws a mandible, 9 

 or upper, and a maxilla, or lower jaw, on each 

 side. The labium, or lower lip, is divisible 

 into two parts a inentum, or basal joint, 

 and a more flexible piece moving on this, the 

 ligula, or labium proper. On the inner sur- 

 face of this labium is developed a small pro- 

 cess having a certain resemblance to a tongue, 

 situated in front of the cesophageal orifice, 



and generally anchylosed with the labium at 



Vertical section of head of Limax maximus, 



niiu ^cuuiaiiv aiiLii v luacu wnu uic laL/iuiii ill -i '* -^""uj. IHUAIIILUS, 



the front and sides of that opening ; in some fi^.^JSLJ^ of the mouth > a ' 



cases, however, as m the locusts and dragon Retracted proboscis of Buccinum undatum. a, 



flies, it is tree. 1ms process Cuvier con- mouth; b, tongue; c, oesophagus. 



sidered merely as a part of the labium, and 

 accordingly called it labium ; Fabricius and 



, . 



B, single row of tongue-teeth of B. undatum. 



accordingly called it laoium ; J?aL>ncius and _,. . 



Latreille gave it the name of ligula. In shape f ihls . membrane is covered on its upper sur- 

 it is generally short, but in bees it is long; it , Wlth transverse rows of minute teeth, or 

 is frequently simple, but in the wasp its apex ralner plates with tubercular or toothlike pro- 

 is trifid, the same in Melolontha stigma ; in ce ^ se . s l 'Pn tliem. The number of rows is 

 Canabus it possesses three short teeth ; in cons . ld erable, and very variable, the terrestrial 

 Elaphras it terminates in a single tooth or s P ecies averaging, probably, about eighty, and 

 point. In substance it generally approaches marine possessing often many more ; the 

 to a cartilaginous consistence, but in the Ort'io- number f plates in each row is subject to 



still greater variation : the common whelk 



ptera and Libellulcs it is much more fleshy: 

 and in the predaceous beetles it is as hard 

 and horny as the integument. In some cases 

 it is immovable, in others projectile and re- 

 tractile within the mouth ; in some cases 

 smooth, in others covered with hairs, as is 

 the case in the common hive-bee ; in Melo- 

 luntha stigma the hairs are incurved In the 



undalum) has but three (fig. 759. 

 B), the large garden slug (Limax maximus) 

 has 180. The shape of die plates in terres- 

 trial gasteropoda is usually irregularly qua- 

 drangular, slightly longer than broad, while in 

 some fluviatile and marine species they as- 

 sume most complicated and elegant forms 



/ _^? . .,/-! T- \ m i 



O I'M*.* HCMIO .11 ^ Jill- LI 1 V tl.1 JL11 ItPIC / j? T\ 



hive-bee the upper part of the tongue is car- 'f^ - ' 59< B '' . The centre plate of the row is 



tilaginous, and remarkable for a number of alwa )' s symmetrical, and its denticular projec- 



transverse rings : below the middle it consists * lon! ? P int m tlle dll 'ection of the closed end, 



of a membrane longitudinally folded in in- ' e ~ bac kwards, and nearly horizontally. The 



action, but capable of being inflated to a con- p j 1168 on elth . er Slde of . this central plate usu- 



siderable size : this membranous ba<>- receives T, y assum f m terrestrial gasteropods much 



the honey which the toncue, as it were laps t ? e ^ am . e form and direction, while some of 



from the flowers, and 'conveys it to the e fluviatll e and most of the marine species 



pharynx.f present such an endless variety of forms, that 



Mollusca. Gasteropoda. In the acephalous f he m ost that can be said of them, generally, 



mollusca there is, of course, no tongue. But 1 ^, that the dental processes point backwards, 



the Gasteropoda are provided with a very sin- f' 7o9 ' B represents a row of the denti- 



gular apparatus, which, since it is usually called g erous tongue-plates of the Buccinum undo- 



the tongue, cannot be allowed to pass obser- tun \ : there are se f n to be onl >' three ; the cen- 



vation here, though its right to such an ap- t , ra one s y mm etncal, the lateral ones of very 



pellation is somewhat questionable. Its form dlfferen t, form, individually non-symmetrical, 



is subject to much variation, but it may be having an exact correspondence to one 



described generally as a thin membrane. 'ion- anoth - er ; The tongue itself (Jig. 759. A, 2) is 



._ i , i r> i i . fifturh pn PQ Korrti-A ofofo,-) t^4-U^. ^_u,_ 



generally , 



and narrow, the greater extent of which is 

 rolled into a tube. This tubular part (fg. 759. 

 A, 6), occupies the posterior portion of the 



attached, as before stated, to the oesophagus 

 near its anterior extremity, and lies beneath 

 it. In the Helices and Limaces it is enveloped 



, , e 



membrane, the end being closed, while its an- '"_ ne muscular h ead of the gasteropod (fig. 



terior extremity is open and in connection /, '\ lts P osterior Dl '" d end being just 



with the oesophagus ; in front of the tubular vlslble at the ba ck part of the head, some dis- 



part of the tongue is a continuation of the , tance , ow the P omt where th e oesophagus 



same membrane, which is here flat, and in many . es that P art and passes into the abdominal 



cavity. In the whelk tribe it lies beneath, and 



. n ,, ,', ,. parallel to, the oesophasrus, and is free, though 



* Ce qu on a nomine langue dans les coleopteres !.,,..,.,->,, J i i i ? 



et les orthoptcres, ou 1'extremite membraneuse 'de la sunoilld f. d b 3' st rong muscular bands, the 



levre infe'rieure, en me'rite & eine le nom. Guv. g ener al direction of which is also parallel to 



, 



levre infe'rieure, en me'rite & peine le nom. Guv., 

 Le9ons d'Auat. Comp., t. iii. p. 347. 

 f Kirby and Spence, vol. iii. p. 453 



g ener a irection o wic is aso par 



It is in this tribe that the an- 

 terior end of the tongue is curved downward, 



