GLOSSARY. 305 



in many Echinoderms, attached to the surface of the body, and resembling 

 a little beak or forceps, supported on a stalk. 

 PEDICLE (Lat. dim. ofpes, the foot). 'A little stem. 



PEDIPALPI (Lat. pes, foot ; andpalpo, I feel). An order of Arachnida com- 

 prising the Scorpions, &c. 



PEDUNCLE (Lat. peduncidus, a stem or stalk). In a restricted sense, applied 

 to the muscular process by which certain Brachiopods are attached, and 

 to the stem which bears the body (capitulum) in Barnacles. 

 PEDUNCULATE. Possessing a peduncle. 

 PELAGIC (Gr. pelagos, sea). Inhabiting the open ocean. 

 PELVIS (Lat. for basin). Applied, from analogy, to the basal portion of the 



cup (calyx) of Crinoids. 



PEKGAMENTACEOUS (Lat. pergamena, parchment). Of the texture of parch- 

 ment. 

 PERIDERM (Gr. peri, around; and derma, skin). The hard cuticular layer 



which is developed by the ccenosarc of certain of the Hydrozoa. 

 PERIGASTRIC (Gr. peri, around; and gaster, stomach). The perigastric space 

 is the cavity which surrounds the stomach and other viscera, correspond- 

 ing to the abdominal cavity of the higher animals. 

 PERIOSTRACUM (Gr.pcri; and ostrakon, shell). The layer of epidermis which 



covers the shell in most of the Mollusca. 

 PERIPLAST (G-r. peri ; and plasso, I mould). The intercellular substance or 



matrix, in which the organised structures of a tissue are imbedded. 

 PERISOME (Gr. peri ; and soma, body). The coriaceous or calcareous inte- 

 gument of the Echinodermata. 



PERISTOME (Gr. peri ; and stoma, mouth). The space which intervenes 



between the mouth and the margin of the calyx in Vorticella ; also the 



space between the mouth and the tentacles in a Sea-anemone (Actinia) ; 



also the lip or margin of the mouth of a univalve shell. 



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



the space surrounding the viscera. 

 PETALOID. Shaped like the petal of a flower. 

 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. 



PHYLACTOLJEMATA (Gr. phulasso, I guard, and laima, throat). The division 

 of Polyzoa, in which the mouth is provided with the arched valvular pro- 

 cess known as the ' epistome.' 

 PHYLLOCYSTS (Gr. phullon, leaf; and Jcustis, a cyst). The cavities 'in the 



interior of the ' hydrophyllia ' of certain of the Oceanic Hydrozoa. 

 PHYLLOFODA (Gr. phullon, leaf; findpous, foot). An order of Crustacea. 

 PHYOGEMMARIA (Gr. phuo, I produce ; and Lat. gemma, bud). The small 



gonoblasticHa 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. ph^lton, 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. 

 PINNUUE (Lat. dim, of pinna). The lateral processes of the arms of 



Crinoids, 

 VOL. I. X 



