392 INDEX-GLOSSARY. 



Platyhelmia (-TrXaTus, flat; e/\/uivs, eX/ui/dos, a worm) Flat worms, 340; 



Chap, iii., 28. 

 Pleura (rXsw/>a, a rib), in Vertebrates The membrane lining the thorax, 



293. 

 Pleuro-branchia (<r*.fupov, a rib ; branchia), in the Crayfish A gill attached 



to an epimeron, 97. 

 Pleuron (**.'. vpov), a rib, 84. 

 Pleuro-peritoneum, in the Frog The membrane lining the body-cavity, 



191. 



Pleuro- peritoneal cavity, in the Frog The body-cavity, 191. 

 Plexus A network ; Brachial p., 254, 303 ; Choroid p., 210, 301 ; Lumbar 

 p., 254; Lumbo-sacral, 303; Nerve-p , 146, 171, 215, 320; Sciatic p., 

 213, 254. 

 Podobranchia (ruj, *obos, a foot ; branchia), in the Crayfish One of the 



gills attached to the bases of the appendages, 97. 

 Polar-cell The cell, or one of the cells cut off from the ovum before it 



develops into the embryo, 26, 73, 143, 207. 

 Pollex The thumb, 176, 230, 281, 338. 

 Polynesia, 349. 

 Polyodon, 349. 



Polype, fresh water = Hydra, q.v. 

 Polypterus, 349. 

 Pons Varolii A band of fibres running transversely across the ventral 



surface of the medulla, at its front end, 302. 

 Pore Excretory p., 31 ; Genital pore, see Aperture ; Dorsal p., 65 ; Ven- 



tral p., 80; Abdominal, 155. 

 Pore-Canal, 90. 

 Portal System A meshwork of capillaries interposed in the course of a 



vein, 143, 165, 199, 247, 291. 

 Position of body, 176, 230, 269, 322; Erect p., 338; p. of fore-limb, 281, 



326; Primitive p., 175. 



Post-axial Lying posterior to the axis, 154, 176. 

 Postzygapophysis An articular process projecting from the posterior end 



of a vertebra's neural arch, 184, 237. 

 Prsezygapophysis An articular process projecting from the anterior side 



of a vertebra's neural arch, 184, 237. 

 Pre-axial Lying anterior to the axis, 154, 176. 

 Prehallux, 176. 



Premolars, in the Rabbit Grinding teeth which succeed the milk molars, 284. 

 Primates, 346, 357. 



Primitive fibrillse Longitudinal elements into which a muscle-fibre or 

 nerve-fibre may break up, 214, 300. 



