Adapted for the purpose of swimming.

The earliest stage in the development of many Crustacea, especially belonging to the lower groups. In this stage the animal has a short body, with indistinct indications of a division into segments, and three pairs of fringed limbs. This form of the common freshwater Cyclops was described as a distinct genus under the name of Nauplius .

The arrangement of the veins or nervures in the wings of insects.

Imperfectly developed females of certain social insects (such as ants and bees), which perform all the labours of the community. Hence, they are also called Workers .

A semitransparent membrane, which can be drawn across the eye in birds and reptiles, either to moderate the effects of a strong light or to sweep particles of dust, etc. , from the surface of the eye.

The simple eyes or stemmata of insects, usually situated on the crown of the head between the great compound eyes.

The gullet.

A great series of secondary rocks, so called from the texture of some of its members, which appear to be made up of a mass of small Egg - Like calcareous bodies.