PARTS or INSECTS. 29 



tentively examined at the base, will be frequently found of a horny sub- 

 stance. 



In the Coleoptera, and in some of the Jlimiptcra (as in Blat/a, Grt/Uus, 

 Sfc), this appendage terminates at the point in a membranaceous sub- 

 stance: — its form is extremely various in the different genera. The 

 Hymenoptera and some Ni'u?'opte/'a have the ligula situated in the 

 same manner; but it is in these concave, and is frequently prolong- 

 ed into a sort of proboacis, which sometimes exceeds the length of the 

 wliole body. It is membranaceous, but of a soft and spongy texture, 

 and well suited for receiving the impressions of taste. This kind of 

 process is extremely well exemplified in the bee. 



Lingua, the Tongue: an involuted tubular organ, which constitutes 

 the whole mouth in lepidopterous insects. This is of a setaceous form, 

 and either very long, as in the FapUio and Sphinx genera j or short, as 

 in most of the Bombi/ces and other moths. It consists of two filamen- 

 tous pieces, which are externally convex, concave within, and connected 

 longitudinally by a suture along the middle above and bencalh. These, 

 in uniting, form a cylinder, tlirough which the ncctareous jiriccs of the 

 flowers on which these insects subsist are drawn up -with fxcility. 

 These two pieces are not very closely united, and may be separated by 

 means of a needle point. When the insect takes its food, this tube is 

 exserted; at other times it is rolled up spiiidly between the palpi. 



Rostrum, or Beak : the part which forms the mouth in many of the 

 hemipterous order of insects. This instrument is moveable, articu- 

 lated, and bent imder the breast. Within, this beak is hjoilow, and 

 contains, as in a sheath, three or more very fine and delicate bristles, 

 the points of which these insects introduce into the body of the ani- 

 mal, or substance of the plants, from wliich they draw nourishnicnt. 

 The rostrum is conspicuous in the genera,C7o«f/(/, Nepa, and Cimcx. 



Proboscis, the Trunk: inserted in the ulace of the mouth in most 



7 J. 



dipterous insects. It is rather tieshy, retractile, of a single piece, and 

 often cylindrical; the end forming two lips, which are of a soft sub- 

 stance, and from the delicacy of their teguments must possess the fa^- 

 culty of taste in a very high degree. Example in the House-fly. 



Lingua, rostrum, and proboscis, are Linnean terms; and are adopted 

 according to the definition of that author. Ligula is a Tabrician ex- 

 pression, indicating a process of the lower lip. 



Haustellum : formed of two or more very small and delicate fila- 

 ments, inclosed in a sheath of two valves. 



Palpi, Fcclci's. These are the small, moveable, filiform organs or 

 appendages, placed at each side of the mouth in tlie generality of in- 

 sects. In some respects they resemble the antenna-, but are more 

 distinctly articulated. They vary in number in different insects, being 

 either two, four, or six, (P/. 10. Jig. ^-ff- and g.) and are commonly in- 

 serted at each side the exterior part of the jaw. In those which have 



