HET 



HEX 



North American lakes (bony pike). See 

 Horn o-cercal. 



5. Hetero-gamous {ydixos, marriage). 

 A term applied, in Botany, to those 

 capitula in which the outer flowers are 

 neuter or female, and the inner herma- 

 phrodite or male : when all the flowers 

 are hermaphrodite, the capitulum is 

 termed homo-gamous. 



6. Hetero-gangliata {ydjyXiov, a nerve- 

 knot). A term applied by Owen to Cu- 

 vier's grand division Mollusca of the 

 animal world, the beings of this division 

 having a ganglionic nervous system, and 

 the ganglions scattered often unsymme- 

 trically. These are the cyclogangliata 

 of Grant. See Homo-gangliata. 



7. Hetero-geneous (yei/o?, kind). A 

 term applied to substances the parts of 

 which are of diflTerent kinds, and there- 

 fore of different qualities. 



8. Helero-mera (/uepof, a part). A sec- 

 tion of coleopterous insects, in which the 

 tarsi are differently parted, the four an- 

 terior being five-jointed, the two poste- 

 rior four-jointed. — Latreille. 



9. Hetero-morphous {fxoptpr], form). Of 

 an irregular or unusual form ; a term 

 applied to the larvae of certain insects 

 which differ in form from the imago, and 

 applicable to the true larval state of all 

 insects. 



10. Hetero-phyllous {^vWov, a leaf). 

 A term applied to those plants in which 

 the leaves are not of the same kind as 

 regards form, &c. 



11. Hetero-poda (ttoi;?, iro66^, a foot). 

 A small order of Gasteropods, including 

 certain families in which the foot is so 

 much compressed, as to constitute a ver- 

 tical muscular lamella, which presents 

 merely a remnant of the ventral sucker, 

 so chyacteristic of the entire class, and 

 which can only be serviceable in per- 

 forming the office of a fin used in swim- 

 ming. 



12. Hetero-ptera {Tnepov, a wing). An 

 order of insects in which the two pairs of 

 wings are of different consistence, the 

 anterior pair being horny or leathery, 

 but generally tipped with membrane. 

 They comprise the land and the water- 

 bugs. 



13. Heter-organa {op'^avov, an organ). 

 By this terra, and that of hom-organa, 

 Schultz has divided the vegetable king- 

 dom into two primary cla>ses, with re- 

 ference to the Rotation, or general motion 

 of the sap: the latter class consisting 

 wholly or in great measure of cellular 

 tissue, and containing all the cellular I 



164 ' 



flowerless, and some flowering, plants of 

 a low organization; the former all the 

 higher flowering plants, and the vascular 

 flowerless. 



14. Hetero-scii (crKui, a shadow). This 

 and some similar terms, as amphi-scii 

 and peri-scii, are of old date, but still 

 remain in works on the use of the globes. 

 The first are the inhabitants of the two 

 temperate zones, the noon-day shadows 

 of each being always thrown one way, 

 but those of the two being always in dif- 

 ferent ways. The second are the inha- 

 bitants of the torrid zone, who have their 

 noon-day shadows sometimes cast north, 

 sometimes south. The third are the in- 

 habitants of the frigid zones, whose vi- 

 sible shadows make complete revolu- 

 tions. 



15. Hetero-tropal (rpeTrco, to turn). 

 That which has its direction across the 

 body to which it belongs, as applied, in 

 Botany, to the embryo of the seed, as in 

 primrose. 



HEU'LANDITE. A mineral formerly 

 ranked among the zeolites, consisting of 

 silica, alumina, and lime, and found in 

 the Faroe Isles, the trap of the Giants' 

 Causeway, &c. 



HE'XAGON (ef, six, -^wvia, an angle). 

 In Geometry, a plane figure bounded by 

 six sides, and consequently having six 

 angles. The side of a regular hexagon 

 is equal to the radius of its circumscri- 

 bing circle. The area is equal to the 

 square of the side multiplied into the con- 

 stant number 2.598076 ; that is, into three 

 times half the tangent of 60°. 



HEXAGY'NIA (ef, six, -^vvh, a wo- 

 man). The name of those orders of 

 plants in the Linnaean system, which are 

 characterized by the presence of six 

 pistils. 



HEXAHE'DRON (ef, six, Upa, a 

 seat). A cube, or a solid geometrical 

 figure, having six faces. The whole sur- 

 face of a hexahedron is equal to 24 times 

 the square of the radius of the inscribed 

 sphere, and to 8 times the square of the 

 radius of the circumscribed sphere. Its 

 solid content is 8 times the cube of the 

 inscribed sphere. 



HEXA'NDRIA (ef, six, iv^jp, a man). 

 The sixth class of plants in the system 

 of Linnaeus, characterized by the pre- 

 sence of six stamens. 



HE'XAPOD (ef, six, ttoi/?, ttoSop, a 

 foot). Six-footed ; a term applied to ani- 

 mals with six legs, as the true insects 

 Hence, the term Hexapoda has been ap- 

 applied by Mr. Kirby to a sub-order of 



