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surrounding water opaque, and thus to 

 conceal themselves. Examples of this 

 contrivance may be seen in the Sepia vul- 

 garis and Loligo of our seas. To Miss 

 Mary Anning we owe the discovery of 

 numerous fossil ink-bags, found in the 

 lias of Lyme Regis, still distended, as 

 when they formed parts of the living ani- 

 mals. The contents of the ink-bags of 

 cephalopods is used in drawing, the sort 

 preferred is from an oriental species of 

 sepia ; some of that extracted from a fossil 

 ink-bag found in the lias was used by Sir 

 Francis Chantrey, on the request of Prof. 

 Buckland, and was by a celebrated painter, 

 who was ignorant of the particulars, pro- 

 nounced to be sepia of excellent quality. 

 This extreme indestructibleness of sepia 

 arises from its being chiefly composed of 

 carbon. 



INOCERA'MUS. A genus of fossil bivalvular 

 shells of the chalk series, with an oblique 

 beak. Dr. Mantell, in his geology of the 

 South' East of England, states, " The 

 shells of the genus inoceramus are very 

 remarkable, and ten species occur in the 

 chalk of the South of England. These 

 shells are more or less gibbous, and are 

 commonly marked with transverse con- 

 centric ridges, and strise ; their consti- 

 tuent substance is invariably composed of 

 crystallized carbonate of lime, of a radiated 

 or fibrous structure. The hinge is a lon- 

 gitudinal furrow, transversely crenulated, 

 extending on one side of the beaks only. 

 One species, the Inoceramus Cuvieri, at- 

 tains a large size ; a length of three feet, 

 by two in width. 



INORGA'NIC. ) Devoid of the organs of 



INORGA'NICAL. $ vitality. 



INO'RGANISKD. Void of organic structure. 



INO'SCULATE. (from in and oscular, Lat.) 

 To unite by apposition. 



INOSCULATION. Union by junction of the 

 extremities ; the union, or junction, of the 

 mouths of vessels, as arteries with veins. 



I'NSECT. (insecta, Lat. insecte, Fr. inset- 

 to, It.) The third class of articulated 

 animals provided with articulated legs ; 

 they possess a dorsal vessel analogous to 

 the vestige of a heart, but are wholly des- 

 titute of any branch for the circulation. 

 Insects breathe atmospheric air by means 

 of trachese, which are most freely ramified 

 through all parts of the body ; they pos- 

 sess compound eyes. All insects, which 

 possess wings, metamorphose, or pass 

 through certain changes, before they ar- 

 rive at their perfect form. In their first 

 state, after leaving the egg, they form 

 larvse, or caterpillars. The bodies of in- 

 sects are divided into head, corslet, pec- 

 tus, abdomen, and members. The head 

 is joined to the body, in some, by ball 

 and socket ; in others, by plain surfaces ; 



in others, after the manner of a hinge. 

 In some, the connection is entirely liga- 

 mentous, the different motions correspond- 

 ing with the nature of the joint. The 

 corslet, or thorax, is situated between the 

 pectus and head. The first pair of feet 

 are joined to this, and it contains the 

 muscles for moving those and the head. 

 To the upper and lateral part of the pec- 

 tus, the wings, when present, are fixed, 

 and the four posterior feet to its under 

 part. To the upper part a horny process 

 is frequently fixed, termed scutellum, or 

 escutcheon. The pectus contains the mus- 

 cles which move the wings and four pair 

 of the feet. Fyfe. 



Cuvier divided insects into twelve or- 

 ders: 1. Myriapoda, or insects having 

 more than six feet, to twenty-four and up- 

 wards ; the insects of this order are apte- 

 rous, that is, destitute of wings. The 

 myriapoda are also called centipedes. 2. 

 Thysanoura ; this order possesses six legs 

 and no wings, and is characterized by the 

 abdomen being furnished with lateral 

 moveable parts, resembling false feet, or 

 appendages fitted for leaping. This order 

 has also been called aptera. 3. Parasita, 

 having six legs, no wings, and ocelli ; the 

 mouth consists of a sort of snout contain- 

 ing a retractile sucker. 4. Suctoria, hav- 

 ing six legs, but not supplied with wings. 

 5. Coleoptera, having six legs and four 

 wings, with a horny case, under which 

 the wings are folded. 6. Orthoptera, 

 having six legs and four wings, the two 

 superior wings in the form of cases, and 

 mandibles and jaws for mastication, co- 

 vered at the extremity by a galea. 7. 

 Hemiptera, having four wings, either 

 stretched straight out, or resting across 

 each other : the blatta, gryllus, fulgora, 

 cymen, &c., are examples. 8. Neurop- 

 tera, having four reticulated wings, the 

 inferior being usually of equal size with 

 the superior ; the libellula, ephemera, &c. 

 are examples. 9. Hymenoptera, having 

 four wings, naked and membranous, and 

 six feet ; these generally possess a sting ; 

 the vespa, apis, formica, termes, &c., are 

 examples. 10. The Lepidoptera, pos- 

 sessing a soft hairy body, and four ex- 

 panded wings, membranous, and covered 

 with small coloured scales resembling 

 dust: the papilio, or butterfly, sphinx, 

 and phalsena, are examples. 11. The 

 Rhipiptera, having two membranous wings, 

 folded like a fan, six legs, and two crus- 

 taceous moveable bodies. This order was 

 established by Mr. Kirby, under the name 

 of Stresiptera, or twisted wings ; two ge- 

 nera are included in it, Stylops and Xe- 

 nos. 12. Diptera, having two membra- 

 nous extended wings and six legs, with, 

 generally, two moveable bodies placed 

 s 



