142 GLOSSARY. 



PHYSOPODA (Qvo-a, bellows; irovs, foot), a group of insects with bladder-like 



feet. 

 PILLIDIUM (for pileolus, dim. of pileus, a felt cap), the name applied by Miiller to 



the helmet-shaped larva of Neinertes, one of the Turbellaria. 

 PINEAL body or "gland" (pt'nna, a fir-cone), otherwise called Conarium ; a 



constant outgrowth from the roof of the Prosencephalon of Vertebrata. 

 PINNULE (pinnula, dim. of pinna or penna, a feather), the secondary branches 



from the quills of a feather, otherwise called barbs. 

 PITUITARY body or " gland " (pituita, phlegm, which it was supposed to secrete), 



a constant appendage of the brain just in front of the Notochord. 

 PLACENTA (a cake), applied to the developed chorion in Mammalia from its discoid 



shape in Man. 

 PLACOLDEI (TTA.O|, a flat plate ; eTSos, likeness), an order of fishes with flat smooth 



integument, the Selachii, or Sharks and Rays : v. ELASMOBRANCHII. 

 PLANTIGRADE (planta, the sole of the foot ; gradior, to walk), applied to those 



animals which apply the whole of the foot, including the heel, to the ground, 



as Man, bears, and badgers. 

 PLESIOSAUKUS (TTATJO-IOS, near ; <rcwpo, a lizard), an extinct genus of marine reptiles 



which gives its name to an order, Pleeiosauria, so called because their 



skeletons were first found associated with those of the Ichthyosaurus. 

 PLEURODONT (u-Aeupa, a rib, side ; oSovs, tooth), the attachment of teeth to the jaw 



in which one side of the fang became ankylosed with the inside of the socket. 

 PLUTEUS (a pent-house, or shed), applied to the " painter's-easel " larva of the 



Echinus. 

 PODOPHTHALMIA (TTOVS, foot ; o<pda\fj.6s, eye), an order of Crustacea in which the 



eyes are stalked or pedunculate ; it corresponds with the group Decapoda. 

 POLLEX, the thumb : the first, innermost, or most praeaxial of the digits of the 



anterior extremity, placed iu a line with the radius. 



POLYCYSTINA (TToXus, many ; KWTTJS, a bladder), the minute shells of Eadiolaria. 

 POLYGASTRICA (iroXw, yaarrip, belly), a name given by Ehrenberg under a wrong 



impression to Infusoria. 

 POLYZOA (TTO\WJ, &ov, animal), a class of compound animals, otherwise called 



Bryozoa ()3piW, moss), from their parasitic habit on sea-weed. 

 PR.EAXIAL and POSTAXIAL are applied respectively to the parts on the radial or 



tibial and those on the ulnar or fibular side of the limbs ; the former being 



internal or anterior, the latter external or posterior, to the axis of the limb. 

 PB.EMOLAR (prse, in front ; molares, grinders), the molar teeth which are preceded 



by milk molars, the bicuspids. 



PRSSPHENOID ( pras, before ; os sphenoidale), the centrum of the third cranial seg- 

 ment, corresponding in human anatomy to the front part of the body of the 



sphenoid bone : v. BASISPHENOID. 

 PBOGLOTTIS (717)07 A.WTTIS, the point of the tongue), applied to the zooids of Scolecida 



which are propagated by gemmation from a scolex, and in their turn produce ova, 

 PRO-OTIC (Trpo", front ; o5s, ear), the anterior ossification of the auditory capsule. 



corresponding in human anatomy with part of the petrous bone. 

 PBOPODITE (irp6, front ; TTOUS, foot), the proximal segment of the typical limb of 



a Crustacean. 

 PROTOPLASM (vpSnos, first ; Tr\d<r/j.a, fr. ir\dffffo>, to form), the primitive indifferent 



tissue of the embryo out of which all subsequent organs are formed by a pro- 

 cess of differentiation. 

 PROTOZOA (irptaros, first ; >ov, animal), the lowest group of animals. A similar 



