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INOPERCULAR. A term applied to univalve 

 shells which have no operculum or lid. 



INORGANIC. Not formed with the organs or 

 instruments of life. 



INOSCULATION. The union of two vessels 

 of an animal body at their extremities, by 

 means of which a communication is main- 

 tained, and the circulation of fluids is 

 carried on. 



INSCRIBED. When the surface is marked with 

 the resemblance of a letter of any language. 



INSECT. A small invertebrate animal, 

 breathing by lateral spiracles, and fur- 

 nished with articulated extremities and 

 movable antennae. 



INSECTILE. Having the nature of insects. 



INSECTIVOROUS. Subsisting on insects. 



INSTINCT. The operation of the principle 

 of organized life, independent of all in- 

 struction or experience, but by which ani- 

 mals are unerringly directed to do spon- 

 taneously whatever is necessary for the 

 preservation of the individual or the con- 

 tinuation of their kind. Astonishing 

 manifestations of the instinctive faculty 

 are continually occurring, and might be 

 given if our space permitted it. 



INSTINCTIVE. Prompted by instinct ; acting 

 spontaneously, without reasoning, instruc- 

 tion or experience. 



INSTRUMENTA CIBARIA. The parts of the 

 mouth in insects concerned in the acquisi- 

 tion and preparation of the food. 



INTACTABLE. Not perceptible to the touch. 



INTEGUMENT. A covering which naturally 

 invests the body, as the skin of an animal 

 or the shell of a crustacean ; or a mem- 

 brane that invests a particular part. 



INTELLECT. The understanding ; that 

 faculty of the human mind which receives 

 or comprehends the ideas communicated 

 to it by the senses or by perception, or by 

 other means. 



INTELLECTUAL. Pertaining to the intellect ; 

 perceived by the understanding, not by 

 the senses. 



INTELLIGENCE. Understanding; skill. The 

 distinctive character of human intelligence 

 over that of the most perfect of other crea- 

 tures, is the faculty which man possesses of 

 representing general ideas by particular 

 signs or images associated with them ; 

 whereas the instincts of animals, however 

 ingenious or complicated, are so truly the 

 property of the species, that all its indivi- 

 duals perform them in the same way, with- 

 out any improvement. 



INTERAMBULACRA. The imperforated plates 

 which occupy the intervals of the perfo- 

 rated ones, or ambulacra, in the shells of 

 Echinoderma. 



INTERCOSTAL. Placed between the ribs ; 

 as, an intercostal muscle, artery, or vein. 



INTERGANGLIONIC. Belonging to the ner- 

 vous chords in the intervals of the gan- 

 glions, which they connect together. 



INTERMAXILLARY. Situated between the 

 jaws. 



INTERMIGRATION. Reciprocal migration. 



INTERMUSCULAR. Between the muscles. 



INTERNODAL. Having a space between one 

 knot or joint and another. 



INTEROCULAR. When the antennas of an 



insect are inserted any where between the 



eyes. 



INTERORBITAL. Situated between the orbits. 

 INTEROSSEOUS. Situated between bones ; as 



an interosseous ligament or muscle. 

 INTERSCAPULAR. Situated between the 



shoulders. 

 INTERSECTED. Cut or divided into parts by 



being crossed. 

 INTERSTICE. In insects, the space between | 



elevations and depressions running in lines. 

 INTERSTITIAL. Relating to the intervals 



between parts. 



INTERTROPICAL. Pertaining to those coun- 

 tries which lie between the tropics. 

 INTERVAL. An entomological term denoting | 



the space between irregular and scattered 



elevations and depressions. 

 INTESTINAL. Pertaining to the intestines of 



an animal body ; as, the intestinal tube or i 



canal. 

 INTROMIT. To enter, or to allow to enter ; 



to be the medium by which a thing enters j 



or is admitted. 

 INTHOSUSCEPTION. The passing of one part | 



of an intestine within another, causing a 



duplicature of it. 

 INTRUDED. When the head of an insect is 



nearly withdrawn within the trunk. 

 INVERTEBRATE. Destitute of a backbone or 



vertebral chain. 

 INVOLUTE. Rolled inwards. Where the 



exterior lip of a shell is turned inwards at 



the margin, as in the Cypraea. 

 IRIDESCENT. Having colours like the rain- 

 bow. 

 IRIS (plu. irides). The coloured circle which 



surrounds the pupil of the eye, by means 



of which that opening is enlarged and 



diminished. 

 IRRADIATED. Made luminous, bright, or 



shining. 



IRRESPIRABLE. Unfit for respiration. 

 IRRIGATE. To water, as land, by causing a 



stream to flow upon it and spread over it. 

 IRRORATED. Sprinkled or moistened with 



atoms, as the earth with dew. 

 ISABEL or ISABELLA-COLOUR. A brownish 



yellow colour, with a shade of dark red. 

 ISCHIADIC (from ischium, the hip). Per- 

 taining to a rheumatic affection of the hip 



joint, generally termed sciatica. 

 ISLET. In entomology, a spot of a diiferent 



colour, included in a plaga or macula. 

 ISOPODA. An order of Crustaceans in which 



the feet are alike, and equal. 

 ISOLATED. Detached from others of a like 



kind ; standing alone. 

 ITINERANT. Wandering ; not settled. 



JUNCTURE. A joint or articulation ; a seam 



or line at which an union between two 



bodies is effected. 

 JUGULAR. Pertaining to the neck or throat ; i 



as the jugular vein. 

 JUBATE. Having long pendent hairs in a 



continued series, as in some iusects. 



KNAG. The shoot of a deer's horns. 



KNEE-BRUSHES. The tufts of hair on the 

 knees of some antelopes ; also, the tlxick- j 

 set hairs on the legs of bees, with which 

 they carry the pollen to the hive. 



