Ganglion

(Gr. gagglion, a knot). A mass of nervous matter containing nerve-cells, and giving origin to nerve-fibres.

Ganoid

(Gr. ganos, splendour, brightness). Applied to those scales or plates which are composed of an inferior layer of true bone covered by a superior layer of polished enamel.

Ganoidei

An order of Fishes.

Gasteropoda

(Gr. gaster, stomach; pous, foot). The class of the Mollusca comprising the ordinary univalves, in which locomotion is usually effected by a muscular expansion of the under surface of the body (the "foot").

Gastrula

(Gr. dim. of gaster, stomach). A name applied by Haeckel to that developmental stage in various animals, in which the embryo consists of two fundamental membranes, an outer and an inner, enclosing a central cavity.

Gemmae

(Lat. gemma, a bud). The buds produced by any animal, whether detached or not.

Gemmation

The process of producing new structures by budding.

Gemmiparous

(Lat. gemma, a bud; pario, I produce). Giving origin to new structures by a process of budding.

Gemmules

(Lat. dim. of gemma). The ciliated embryos of many Coelenterata; also the seed-like reproductive bodies or " spores " of Spongilla.

Gephyrea

(Gr. gephura, a bridge). A class of the Anarthropoda, comprising the Spoon-worms (Sipunculus) and their allies.

Gizzard

A muscular division of the stomach in Birds, Insects, etc.

Gladius

(Lat. a sword). Applied to the horny endoskeleton or "pen" of certain Cuttle-fishes.

Glenoid

(Gr. glene, a cavity; eidos, form). A shallow cavity ; applied especially to the shallow articular cavity in the shoulder-blade to which the head of the humerus is jointed.

Gnathites

(Gr. gnathos, a jaw). The masticatory organs of Crustacea.

Gonangium

(Gr. gonos, offspring; and aggeion, a vessel). The chitinous receptacle in which the reproductive buds of certain of the Hydrozoa are produced.

Gonoblastidia

(Gr. gonos, offspring; blastidion, dim. of blastos, a bud). The processes which carry the reproductive receptacles, or "gonophores," in many of the Hydrozoa.

Gonocalyx

(Gr. gonos; and kalux, cup). The swimming-bell in a medusiform gonophore, or the same structure in a gonophcre which is not detached.

Gonophore

(Gr. gonos; and phero, I carry). The generative buds, or receptacles of the reproductive elements, in the Hydrozoa, whether these become detached or not.

Gonosome

(Gr. gonos; and soma, body). Applied as a collective term to the reproductive zooids of a Hydrozoon.

Gonotheca

(Gr. gonos; and theke, a case). The chitinous receptacle within which the gonophores of certain of the Hydrozoa are produced.

Gballatores

(Lat. gralloe, stilts). The order of the long-legged "Wading Birds.