8 10 GLOSSARY. 



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 Amos, a cone). The chambered 



portion of the internal shell of a Belemnite. 



PHYLACTOL.EMATA (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." 



PHYLLOOYSTS (Gr. phullon, leaf; and kustis, a cyst). The cavities in the in- 

 terior of the u 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, bud). The small 



gonoblastidia of Velella, one of the Physophoridce. 



PHYSOGRADA (Gr. phusa, bellows or air-bladder ; and Lat. gradior, I walk). 

 Applied formerly to the Physophoridce, an order of Oceanic Hydrozoa, in 

 which a " float" is present. 

 PHYSOPHORIDCE (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 Carni- 

 vora, comprising the Seals and Walruses, adapted for an aquatic life. Often 

 called Pinnipedia* 



PINNULE (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 vascu- 

 lar 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. 

 PLANULA (Lat. planus, flat). The oval ciliated embryo of certain of the 



Invertebrates. 



PLASTRON. The lower or ventral portion of the bony case of the Chelonians. 

 PLATYELMIA (Gr. plains, broad ; and helmins, an intestinal worm). The 



division of Scolecida comprising the Tape-worms, &c. 

 PLATYRHINA (Gr. platus, broad ; rhines, nostrils). The group of the Quad- 



rumana. 

 PLEURA (Gr. the side). The serous membrane covering the lung in the air- 



brecithing Vertebrates. 



PLEURON (Gr. pleuron, a rib). The lateral extensions of the shell of Crustacea. 

 PLUTEUS (Lat. a pent-house). The larval form of the Echinoidea. 

 PNEUMATIC (Gr. pneuma, air) Filled with air. 

 PNEUMATOCYST (Gr. pneuma, air ; and kustis, cyst). The air-sac or float of 



certain of the Oceanic Hydrozoa (Physophoridce). 



PNEUMATOPHORE (Gr. pneuma, air ; and phero, I carry). The proximal 

 dilatation of the coenosarc in the Physophoridce which surrounds the pneu- 

 matocyst. 

 PNEUMOSKELETON (Gr. pneuma; and skeletos, dry). The hard structures which 



are connected with the breathing organs (e.g., the shell of Molluscs). 

 PODOPHTHALMATA (Gr. pous, foot ; and ophthalmos, eye). The division of 

 Crustacea in which the eyes are borne at the end of long foot-stalks. 



