Index and Glossary. 



141 



osc 



Osculum, the mouths in sponges, 



Ostracoda, minute crustaceans, 107 



Ovipositor, the organ whereby in- 

 sects deposit their eggs, 121 



Ovulation, the mode of reproduction 

 by the development of eggs, 5 



Oxytricha, 25 



Oxyuris, a worm, 63 



Oyster, 85 



PALAEOZOIC, the age of the 



world in which the oldest fossil- 

 bearing rocks were formed, 



Pallial line, the line on a shell indi- 

 cating the margin of the mantle, 

 83 



Palp, a feeler or jointed appendage 

 on the jaw of an arthropod. 



Paraglossae, part of an insect's 

 mouth, 117, 133 



Paramcecium, a common infusory 

 animalcule, 26 



Parasites, 17 



Pauropods, 114 



Pedicellariae, jointed pincer-like ap- 

 pendages to the mouth in Echino- 

 dermata, 51 



Pedicelli, small sucking feet in star- 

 fishes, 49 



Pennatula, a sea-pen, 46 



Pennella, a parasitic crustacean, 

 105 



Pentastoma, a parasitic mite, 10 



Pericardium, the space of the body 

 cavity around the heart, 



Periplaneta, the cockroach, 125 



Pharynx, the upper part of the di- 

 gestive tube near the mouth. 



Physalia, 37 



Physiology, the science which treats 

 of the functions of organs, 7 



Pixinia, a gregarine, 23 



Planula, the ciliated embryo of a 

 jelly-fish, 33 



Pluteus, the larval stage of a star- 

 fish, 51 



Podophthalmia, crabs, &c., whose 

 eyes are on stalks, 107 



Podure, 124 



Poecilopoda, king-crabs, 103 



Polycelis, a Uibellarian worm, 59 



Polypites, hydra-like animals when 



in colonies, 35 

 Polystomata, 28 



SEG 



Pores, the fine openings in sponges, 

 3 



Postabdomen, that part of the ab- 

 domen behind the openings of the 

 reproductive organs, 101 



Proglottis, one of the mature joints 

 of a tape-worm, 61 



Protamoeba. one of the simplest 

 known animals, 21 



Protoplasm, 2 



Protoplasta, amoebae, 22 



Protozoa, 14, 18 



Provisional organs, those organs 

 that fulfil a temporary function, 

 and then disappear or waste, 8 



Pseudonavicellae, 23 



Pseudopodia, 3, 19 



Pteropoda, 89 



Ptinus, 132 



Pupa, the quiescent stage in the 

 life of a butterfly before the per- 

 fect imago condition is reached, 



121 



Pyrosoma, a luminous marine mol- 

 lusc, 77 



D ADIOLARIA, 24 



1V Raphiophora, Neptune's Cup, 



a sponge, 31 

 I Reproduction, 5 



Rhizopods, 18 

 i Rhizostoma, a jelly-fish, 39 



Rhynchota, an order of insects, in- 



eluding bugs, 123 

 Rotatoria, wheel animalcules, 66 

 Rotifer, a common wheel animalcule, 



67 

 Rudimental organ, an imperfect, 



functionless structure, 9 



C ALPA, a pelagic mollusc, 77 

 ** Sandhoppers, small crusta- 

 ceans, 105 

 Scallops, 84 

 Scaphopoda an order of molluscs, 



Scolopendra a centipede, 114 



Scolytus, a wood-boring insect, 131 



Scorpion-flies ^27 



Scorpions, 112 



Sea-cucumbers, 56 



Sea-glue, 25 



Sea-urchins, 47, 53 



Segment, one of the successional 



