Homogangliate

(Gr. homos, like ; gagglion, a knot). Having a nervous system in which the ganglia are symmetrically arranged (as in the Annulosa, for example).

Homologous

(Gr. homos; and logos, a discourse). Applied to parts which are constructed upon the same fundamental plan.

Homomorphous

(Gr. homos; and morphe, form). Having a similar external appearance or form.

Humerus

The bone of the upper arm (brachium) in the Vertebrates.

Hyaline

(Gr. hualos, crystal). Crystalline or glassy.

Hydatids

(Gr. hudatis, a vesicle). The vesicle containing the larval forms (Echinococci) of the tape-worm of the dog.

Hydraform

Resembling the common fresh-water polype (Hydra) in form.

Hydranth

(Gr. hudra, water-serpent; and anthos, flower). The "polypite" or proper nutritive zooid of the Hydrozoa.

Hydrocaulus

(Gr. hudra, a water-serpent; and kaulos, a stem). The main stem of the coenosarc of a Hydrozoon.

Hydrocysts

(Gr. hudra; and kustis, a cyst). Curious processes attached to the coenosarc of the Physophoridae, and termed " feelers " (Fuhler and Taster of the Germans.

Hydroecium

(Gr. hudra,; and oikos, a house). The chamber into which the coenosarc in many of the Calycophoridae can be retracted.

Hydroida

(Gr. hudra; and eidos, form). The sub-class of the Hydrozoa, which comprises the animals most nearly allied to the Hydra.

Hydrophyllia

(Gr. hudra; and phullon, a leaf). Overlapping appendages or plates which protect the polypites in some of the oceanic Hydrozoa (Calycophoridae and Physophoridoe). They are often termed "bracts," and are the "Dechstucke " of the Germans.

Hydrorhiza

(Gr. hudra ; and rhiza, root). The adherent base or proximal extremity of any Hydrozoon.

Hydrosoma

(Gr. hudra; and soma, body). The entire organism of any Hydrozoon.

Hydrotheca

(Gr. hudra; and theke, a case). The little chitinous cup in which the polypites of the Sertularida and Campanularida are protected.

Hydrozoa

(Gr. hudra; and zoon, animal). The class of the Caelenterata, which comprises animals constructed after the type of the Hydra.

Hymenoptera

(Gr. humeri, a membrane; pteron, a wing). An order of Insects (comprising Beetles, Ants, etc.) characterised by the possession of four membranous wings.

Hyoid

(Gr. U; eidos, form). The bone which supports the tongue in Vertebrates, and derives its name from its resemblance in man to the Greek letter U.

Hypostome

(Gr. hupo, under ; stoma, month). The upper lip, or "labrum," of certain Crustacea (e.g., Trilobites).

Hyracoidea

(Gr. hurax, a shrew; eidos, form). An order of the Mammalia constituted for the reception of the single genus Hyrax.

Ichthyodorulite

(Gr. ichthus, fish; dorus, spear; lithos, stone). The fossil fin-spines of Fishes.