GLOSSAKV. 369 



HoLOTHUROlDEA (Gr. holo'Jwurion). The order of Eddnodermata, comprising 



tlie Sea-cucumbers. 

 HoMOCERCAL (Gr. homos, same ; kerkos, tall). Applied to the tail of fishes 



when the two lobes are equal. 

 Homogeneous (Gr. homos, same ; genos, kind). Of like kind or nature, 

 HOMOLOGODS (Gr. homos, same ; logos, a discourse). Applied to parts which 



are constructed upon the .same fundamental plan. 

 HoMOMOKPHOUS (Gr. homos, same ; morphS, form). Having a similar external 



appearance or form. 

 Humerus. The bone of the upper arm in Veriehrata. 

 Hydatid (Gr. hudalis, a vesicle). The bladder-worm of one of the tape-worms 



of the dog. 

 Hydra (Gr. hiidra, a water-serpent). The generic name of the Fresh-water 



Polypes. 

 Hydroida (Gr. hudra ; and eidos, form). The sub-class of the Hydrozoa, con- 

 taining the animals most nearly allied to the Hydra. Often spoken of as the 



Hydroid Zoophytes. 

 Htdrorhiza (Gr. hudra; and rhiza, root). The adherent base or proximal 



extremity ot any .ffydrozoon. 

 Hy-drosoma (Gr. hvdra; and soma, body). The entire organism of any 



Hydrozoon. 

 Hydrotheca (Gr. hudra; thekS, a case). The little chitinous cups in wliieh 



the polypites of the Sertularida and C'ampanularida are protected. 

 Hydrozoa (Gr. hudra ; zoon, animal). The class of the C<elenterata wliich 



comprises animals constructed after the type of the Hydra. 

 Hymknoptera (Gr. hvmen, a membrane ; pteron, a wing). An order of Insects 



(comprising Bees, Ants, &c.) with four membranous wings. 

 Hyoid (Gr. U ; eidos, form). A bone which supports the tongue, and which 



derives its name from its resemblance in man to the letter U. 

 Hybaooidea (Gr. hurax, a shrew ; eidos, form). An order of Mammalia. 



ICHTHYOMORPHA (Gr, ichthus, a fish ; morphe, shape). An order of Amphibia, 



comprising tlie fish-like Newts, &:c. 

 ICHTHYOPHTHIRA (Gr. ichthus, a fish ; phtheir, a louse). An order of 



Crustacea. 

 ICHTHYOPSIDA (Gr. ichthits, fish ; opsis, appearance). The primary division of 



the Vertebrata, which includes the two classes of the Amphibia and Pisces. 

 ICHTHYOPTERYGIA (Gr. ichthus, a fish ; pterux, a wing). An extinct order of 



Reptiles. 

 loHTHYOSAURiA (Gr. ichthus, a fish ; saura, a lizard). An extinct order of 



Reptiles. 

 Imago ( Lat. an image or apparition). The perfect insect, after it has passed 



through all its metamorphoses. 

 Incisor (Lat. incido, I cut). The cutting teeth fixed in the front of the upper 



jaw, and the corresponding teeth in the lower jaw, of the Mammalia. 

 Inequilateral. Having the two sides unequal, as is the case with the shell 



of the ordinary bivalves {Lamellibranchiata). 

 Inequivalve. Composed of two unequal pieces or valves, as is the case with 



the shells of the Brachiopoda. 

 Infusoria (Lat. infitsum, an infusion). A class of Protozoa, so called from 



their frequent occurrence in organic infusions. 

 Insecta (Lat. inseco, I cut into). The class of Articulate animals commonly 



known as Insects. 

 Insectivora (Lat. insectum, an insect ; voro, I devour). An order of Mam- 

 malia. 

 Insectivorous. Living upon Insects. 

 Interambulacra (Lat. inter, between ; ambulacrum, a place to walk in). The 



rows of plates in an Echinus which are not perforated for the emission of the 



tube-feet. 

 Intussusception (Lat. intus, within ; suscipio, I take up). The act of taking 



foreign matter into a living being. 



