GLOSSAKT. 291 



Prostcmium. The segment bearing the rudimentary head in the 

 Annelida. 



Prothorax. The anterior segment of the thorax in insects. 



Protoplasm. " The physical basis of life." An albuminoid sub- 

 stance, homogeneous in the first instance, but capable of assi- 

 milation and differentiation. It is a compound of hydrogen, 

 oxygen, nitrogen, and carbon. Protein and white-of-egg are 

 very nearly identical with it. 



Protopodite. The basal division of the appendages of a segment 

 of a Crustacean. 



Proventriculus. The dilated inferior portion of the oesophagus 

 in birds. 



Pseudo-hcemal system. In Annelids, canals filled up by a clear 

 red or greenish fluid. 



Pseudonavicell(B. Peculiar bodies developed by the Gregarinida. 



Pseudonychium. See Plantula. 



Pseudopodia. Extensions of the sarcode in the Ehizopoda, act- 

 ing as feet and as organs of prehension. 



Pseudova. Eggs of the Aphides, hatched without fecundation. 



Pseudovaria. Ovaries which produce gemmules in cases of par- 

 thenogenesis. 



Pterygoda. See Tegulce. 



Pterygoid. The wing-like process on each side of the sphenoid ; 

 it is a distinct bone in the lower Mammalia. 



PterylcB. The bands or tracts marking the grouping of feathers. 



Pulvillus. A tuft of hairs attached to the underside of the 

 tarsal joints in some insects. 



Pupa. That stage in the life of an insect before it assumes the 

 perfect or imago form. 



Pygidium. The rump ; a general term for the posterior part of 

 the body. 



Quadrate hone. A bone which is placed between the upper and 

 lower jaws in reptiles and birds. 



Radius. One of the bones of the forearm (antebrachiutn). 



Eectrices. The quill-feathers of a bird's tail. 



Redice. The tadpole-shaped larvae of the Digeneous worms when 



they have thrown off their ciliated skin. 

 Eemiges. The quill-feathers of a bird's wing. 



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