Equivalve

(Lat. aequus, equal; valvae, folding-doors). Applied to shells which are composed of two equal pieces or valves.

Errantia

(Lat. erro, I wander). An order of Annelida, often called Nereidea, distinguished by their great locomotive powers.

Eurypterida

(Gr. eurus, broad; pteron, wing). An extinct sub-order of Crustacea.

Exopodite

(Gr. exo, outside; pous, foot). The outer of the two secondary joints into which the typical limb of a Crustacean is divided.

Exoskeleton

(Gr. exo, outside; skeletos, dry). The external skeleton, which is constituted by a hardening of the integument, and is often called a " dermoskeleton."

Fasciculated

(Lat. fasciculus, a bundle). Arranged in bundles.

Fauna

(Lat. Fauni, the rural deities of the Romans). The general assemblage of the animals of any region or district.

Femur

The thigh-bone, intervening between the pelvis and the bones of the leg proper (tibia and fibula).

Fibula

(Lat. a brooch). The outermost of the two bones of the leg in the higher Vertebrata ; corresponding to the ulna of the fore-arm.

Filiform

(Lat. filum, a thread ; forma, shape). Thread-shaped.

Fissilinguia

(Lat. findo, I cleave ; lingua, tongue). A division of Lacertilia, with bifid tongues.

Fission

(Lat. findo, I cleave). Multiplication by means of a process of self-division.

Fissiparous

(Lat. findo ; and pario, I produce). Giving origin to fresh structures by a process of fission.

Fissirostbes

(Lat. findo, I cleave; rostrum, beak). A sub-order of the Perching Birds.

Flagellum

(Lat. for whip). The lash-like appendage possessed by many Infusoria, which are therefore said to be " flagellate."

Flora

(Lat. Mora, the goddess of flowers). The general assemblage of the plants of any region or district.

Foot-jaws

The limbs of Crustacea, which are modified to subserve mastication.

Foot-secretion

The term applied by Mr Dana to the sclerobasic corallum of certain Actinozoa.

Foot-tubercles

The unarticulated appendages of the Annelida, often called parapodia.

Foraminifera

(Lat. foramen, an aperture; fero, I carry). An order of Protozoa, usually characterised by the possession of a shell perforated by numerous pseudopodial apertures.

Frugivorous

(Lat. frux, fruit-; voro, I devour). Living upon fruit.

Furculum or Furcula

(Lat. dim. of furca, a fork). The "merry-thought" of birds, or the V-shaped bone formed by the united clavicles.

Fusiform

(Lat. fusus, a spindle; and forma, shape). Spindle-shaped, or pointed at both ends.

Gallinacei

(Lat. gallina, a fowl). Sometimes applied to the whole order of the Rasorial Birds, but properly restricted to that section of the order of which the common Fowl is a typical example.