Polytrochal

(Gr. polus, many; trochos, wheel). An epithet applied to those larvae of Annelides and other Invertebrates, in which there are successively-disposed circlets of cilia.

Polyzoa

(Gr. polus; and zoon, animal). A division of the Molluscoida, comprising compound animals, such as the Sea-mat. Sometimes called Bryozoa.

Polyzoarium

The dermal system of the colony of a Polyzoon (= Polypidom).

Porcellanous

Of the texture of porcelain.

Porifera

(Lat. porus, a pore ; and fero, I carry). Sometimes used to designate the Foraminifera, or the Sponges.

Post-abdomen

That portion of the "abdomen" of Crustacea, Arachnida, and Myriapoda which lies behind the segments corresponding with the abdomen of Insects.

Post-anal

Situated behind the anus.

Post-oesophageal

Situated behind the gullet.

Post-oral

Situated behind the mouth.

Prae-maxillae

(See Intermaxillae.)

Praemolars

(Lat. pros, before; molares, the grinders). The molar teeth of Mammals which succeed the molars of the milk-set of teeth. In man, the bicuspid teeth.

Prae-oesophageal

Situated in front of the gullet.

Prae-sternum

The anterior portion of the breast-bone, corresponding with the manubrium sterni of human anatomy, and extending as far as the point of articulation of the second rib.

Pressirostres

(Lat. pressus, compressed; rostrum, beak). A group of the Grallatorial Birds.

Proboscidea

(Lat. proboscis, the snout). The order of Mammals comprising the Elephants.

Proboscis

(Lat. or Gr. the snout). Applied to the spiral trunk of Lepidop-terous Insects, to the projecting mouth of certain Crinoids, and to the central polypite in the Medtusoe.

PROCOELOUS

(Gr. pro, before; koilos, hollow). Applied to vertebrae, the bodies of which are hollow or concave in front.

Proglottis

(Gr. for the tip of the tongue). The generative segment or joint of a Tape-worm.

Pro-legs

The false abdominal feet of Caterpillars.

Pronation

(Lat. pronus, lying on the face, prone). The act of turning the palm of the hand downwards.

Propodium

(Gr. pro, before; pous, foot). The anterior part of the foot in Molluscs.

Proscolex

(Gr. pro, before; scolex, worm). The first embryonic stage of a Tape-worm.

Prosobranchiata

(Gr. proson, in advance of; bragchia, a gill). A division of Gasteropodous Molluscs in which the gills are situated in advance of the heart.

Prosoma

(Gr. pro, before ; soma, body). The anterior part of the body.

Prothorax

(Gr. pro; and thorax, chest). The anterior ring of the thorax of insects.

Protophyta

(Gr. protos, first; and phuton, plant). The lowest division of plants.