HEP 



[214] 



HEP 



to certain combinations, called by 

 others hydrosulphurets. 



HEPTACA'PSULAE. (from eWa, Gr. and 

 capsula, Lat.) Having seven cells. 



HE'PTAGON. (heptagone et eptagone, 

 Er. ettagono, It. eVra and <yaWa, 

 Gr.) A figure having seven sides 

 and as many angles. 



HEEBA'CEOUS. (herlaceus^at.} Plants 

 that perish annually down to the 

 roots, having succulent stems or 

 stalks. Of herbaceous plants, some 

 are annual, these perish, stem and 

 root, every year; some are biennial, 

 the roots subsisting two years ; 

 others are perennial, being perpe- 

 tuated for many years by their 

 roots, a new stem springing up 

 every year. 



HEEMA'PHEODITE. (from "E/j/wjs, Mer- 

 cury, and 'A0/)o/T?y, Yenus, h&rma- 

 phodite, Er. ermaphrodito, It. A 

 fabulous name, compounded of those 

 of Mercury and Yenus, Hermes and 

 Aphrodite.) 



1 . Having both the male and female 

 parts of generation. 



2. In botany, plants are so called 

 which contain both stamens and 

 ovarium, in centra-distinction to 

 monoecious and dioecious plants. 



HEEMETIC SEAL, (from Hermes, the 

 reputed inventor of chemistry.) 

 When the neck of a glass vessel 

 or tube is heated to the melting 

 point and then twisted with pincers 

 till it become air-tight, the vessel 

 or tube is said to be hermetically 

 sealed, or to have received the 

 seal of Hermes. 



HEEPETO'LOGY. (cpTre-ros and Xo'ryoe, 

 Gr.) That branch of natural his- 

 tory which treats of reptiles, their 

 habits, &c. 



HE'ESCHELITE. A mineral of a white 

 colour, found by Herschel in oiivine, 

 and named after its discoverer. 



HETEEOCEECAL. Professor Jukes says, 

 Eish have two forms of tail, the 

 one homocercal, that is in which the 

 caudal fin is equally spread round 

 the termination of the vertebral 



column, as in the cod, perch, &c. ; 

 and the other heterocercal, where 

 the vertebral column is, as it were, 

 continued into the upper lobe of 

 the caudal fin, the extremity of the 

 body in reality being slightly bent 

 up, as in the dog-fish, shark, and 

 sturgeon. It is a very remarkable 

 fact, that in all fish, whether osse- 

 ous or cartilaginous, found in the 

 rocks more ancient than the lias, 

 the tails are heterocercal, while in 

 the lias and more recent rocks, the 

 majority of fish have homocercal tails. 



HETERO'CLITAL. In conchology, re- 

 versed; a term applied to shells 

 whose spires turn in a contrary 

 direction to the usual way ; sinis- 

 tral. In shells, the axis of revolu- 

 tion is termed the columella, and 

 the turns of the spiral are denomi- 

 nated whorls. In consequence of 

 the situation of the heart and great 

 blood-vessels relatively to the shell, 

 the left side, or the mantle, is more 

 active than the right side, so that 

 the lateral turns are made in the 

 contrary direction. Sometimes, in 

 consequence of the heart being 

 placed on the right side the turns 

 of the spiral are made to the left : 

 this left-handed convolution seldom 

 occurs among the shells of land or 

 fresh-water mollusca. 



HETEEO'POEA. The name given by 

 De Elainville to a genus of corals. 

 A species established by Mr. Lons- 

 dale, and by him named H. crassa, 

 found ia the Wenlock limestone, 

 is thus described in Sir E. Murchi- 

 son's Silurian System ; " branched, 

 the branches thick, tubes small, 

 radiating from a centre ; transverse 

 fracture; concentric layers formed 

 of two systems of tubes, one visible 

 to the naked eye, the other micro- 

 scopic, numerous and close together. 



HETEEO'STEOPHE. (erepoaTpofai, Gr. 

 ex credos et ff^po(prj.} A term 

 applied to reversed shells, or shells 

 whose spires turn in a contrary 

 direction to the usual way ; sinis- 



