Perivisceral

(Gr. peri; and Lat. viscera, the internal organs). Applied to the space surrounding the viscera.

Petaloid

Shaped like the petals of a flower.

Phalanges

(Gr. phalanx, a row). The small bones composing the digits of the higher Vertebrata. Normally each digit has three phalanges.

Pharyngobranchii

(Gr. pharugx, pharynx; bragchia, gill). The order of Fishes comprising only the Lancelet.

Pharynx

The dilated commencement of the gullet.

Phragmacone

(Gr. phragma, a partition; and konos, a cone). The chambered portion of the internal shell of a Belemnite.

Phylactolaemata

(Gr. phulasso, I guard; and laimos, throat). The division of Polyzoa in which the mouth is provided with the arched valvular process known as the "epistome."

Phyllocysts

(Gr. phullon, leaf; and kustis, a cyst). The cavities in the interior of the "hydrophyllia" of certain of the Oceanic Hydrozoa.

Phyllopoda

(Gr. phullon, leaf; and pous, foot). An order of Crustacea.

Phyogemmaria

(Gr. phuo, I produce ; and Lat. gemma, hud). The small gonoblastidia of Velella, one of the Physophoridos.

Physograda

(Gr. phusa, bellows or air-bladder ; and Lat. gradior, I walk). Applied formerly to the Physophoridoe, an order of Oceanic Hydrozoa, in which a "float" is present.

Physophoridae;

(Gr. phusa, air-bladder; and phero, I carry). An order of Oceanic Hydrozoa.

Phytoid

(Gr. phuton, a plant; and eidos, form). Plant-like.

Phytophagous

(Gr. phuton, a plant; and phago, I eat). Plant-eating, or herbivorous.

Pinnate

(Lat. pinna, a feather). Feather - shaped, or possessing lateral processes.

Pinnigrada

(Lat. pinna, a feather ; gradior, I walk). The group of Carnivora, comprising the Seals and Walruses, adapted for an aquatic life. Often called Pinnipedia, PINNULAE (Lat. dim. of pinna). The lateral processes of the arms of Crinoids.

Pisces

(Lat. piscis, a fish). The class of Vertebrates comprising the Fishes.

Placenta

(Lat. a cake). The "after-birth," or the organ by which a vascular connection is established in the higher Mammalia between the mother and the foetus.

Placental

Possessing a placenta, or connected with the placenta.

Placoid

(Gr. plax, a plate; eidos, form). Applied to the irregular bony plates, grains, or spines which are found in the skin of various fishes (Elasmobranchii).

Plagiostomi

(Gr. plagios, transverse ; stoma, mouth). The Sharks and Rays, in which the mouth is transverse, and is placed on the under surface of the head.

Planarida

(Gr. plane, wandering). A sub-order of the Turbellaria.

Plantigrade

(Lat. planta, the sole of the foot; gradior, I walk). Applying the sole of the foot to the ground in walking.