I M B 



[ 126 ] 



I N C 



been but little worn, the crown is some- 

 what of a prismatic form ; widest, and 

 most depressed, in front ; convex poste- 

 riorly, and rather flattened at the sides. 

 As soon as the tooth emerges from the 

 gum it gradually enlarges, and its edges 

 approach each other and terminate in a 

 point, making the upper part of the crown 

 angular ; the edges forming the side of 

 this angle are deeply serrated, or den- 

 tated ; and the teeth exhibit two kinds of 

 provisions to maintain sharp edges along 

 the cutting surface : the first the serrated 

 edge already described ; the second, a 

 provision of compensation for the gradual 

 destruction of this edge, by substituting 

 a plate of thin enamel, to maintain a cut- 

 ting power in the anterior portion of the 

 tooth, until its entire substance was con- 

 sumed. These teeth were sometimes two 

 inches and a half in length. While the 

 crown of the tooth was diminishing above, 

 an absorption of the fang was proceeding 

 below, caused by the pressure of a new 

 tooth rising to replace the old one, until 

 by continual consumption, both above and 

 below, the middle portion of the older 

 tooth was reduced to a hollow stump, 

 which fell from the jaw to make room for 

 its more efficient successor. The size at- 

 tained by the iguanodon appears to have 

 been enormous, the average length from 

 the snout to the tip of the tail being esti- 

 mated by Dr. Mantell at seventy feet, 

 while, he considers, some may have been 

 one hundred feet in length. This last 

 calculation Prof. Buckland deems impro- 

 bable, but he gives a length of seventy 

 feet to the iguanodon. A thigh-bone in 

 the possession of Dr. Mantell is three 

 feet eight inches long, and thirty-five 

 inches round, at its largest extremity. 

 The length of the hind foot is supposed to 

 have been six feet and a-half ; the cir- 

 cumference of the body, fourteen feet and 

 a-half. A most remarkable appendage 

 possessed by the iguanodon was a horn of 

 bone, placed upon the nose, equal in size, 

 and resembling in form, the lesser horn 

 of the rhinoceros ; here was a further 

 analogy between the extinct fossil igua- 

 nodon and the recent iguana. The base 

 of this nasal horn was of an irregular oval 

 form, and slightly concave. It possessed 

 an osseous structure, and appears to have 

 had no internal cavity. It is evident that 

 it was not attached to the skull by a bony 

 union, as are the horns of the mammalia. 



IMBE'DDED. Inclosed by surrounding mat- 

 ter. 



I'MBIUCATED. (imbricatus, Lat.) Laid 

 one over the other at the edges, like the 

 tiles of a house. In botany, applied to 

 leaves, when lying one over the other like 

 tiles upon a house ; applied also to the 



leaves of the calyx when lying one over 

 the other. 



IMMA'LLEABLE. Incapable of being ex- 

 tended by hammering or beating. 



IMPA'LPABLE. (impalpable, Fr. impalpa- 

 bile, It.) That cannot be felt ; not per- 

 ceptible to the touch ; not gritty. 



IMPE'NNOUS. Wanting wings. 



IMPE'RFORATE. ^ (from in and perforatus, 



IMPE'RFORATED. $ Lat.) Not perforate ; 

 having no opening ; not pierced. 



IMPERMEABILITY. The state of being 

 impermeable. 



IMPE'RMEABLE. Not admitting the passage 

 of fluids through its pores or interstices. 



IMPE'RVIOUS, Impenetrable ; un passable. 



FMPETUS. (impetus, Lat.) Force; vio- 

 lence ; the force with which one body 

 dashes against another. 



IMPI'NGE. (impwi^O, Lat.) To fall against ; 

 to strike against. 



IMPLU'MED. ) (implumis, Lat.) Without 



IMPLU'MOUS. > feathers ; without hair ; 

 callow. 



IMPORO'SITY. Absence of interstices ; 

 closeness of texture to the exclusion of 

 pores. 



IMPO'ROUS. Devoid of pores, of inter- 

 stices. 



INCANDE'SCENCE. (from incandesce, Lat.) 

 White heat. 



INCANDESCENT. White-hot; white from 

 intense heat, far exceeding red-hot. 



INCA'RNADINE. (incarnadin,Fr. incarna- 

 tivo, It.) Bright carnation colour ; of a 

 flesh colour. 



I'NCAVATED. (incavatus, Lat.) Hol- 

 lowed ; scooped out ; made hollow. 



INCAVA'TION. A hollow place. 



INCI'NERATE. To burn to ashes. 



INCINERA'TION. The act of burning to 

 ashes. 



INCI'SOR. (from incisores, Lat.) A fore 

 or cutting tooth. 



INCOHERENCE. } Want of cohesion ; want 



INCOHE'RENCY. \ of adherence. 



INCOHERENT. Wanting cohesion ; un- 

 connected ; loose. 



INCOMBUSTIBLE. (incombustible, Fr.) 

 That will not burn ; that is not consumed 

 by the action of fire. 



INCOMBU'STIBLENESS. The property of 

 resisting the action of fire. 



INCONDE'NSABLE. That cannot be forced 

 into a smaller compass. 



INCO'NGRUOUS. (incongruus, Lat. incon- 

 gru, Fr. inconffruo, It.) Unsuitable ; 

 not fitting. 



INCORPORATE. (incorporo, Lat. incor- 

 porer, Fr. incorporare, It.) To mingle 

 different substances so as to reduce them, 

 to one mass. 



INCRA'SSATE. (incrasso, Lat.) To 

 thicken. 



INCRA'SSATE. (incrassatum, Lat.) Much 



