496 GLOSSARY. 



Ornithodeli'HIa (Gr. ornis, a Mrd ; delphus, womb). The primary divisiou 



of Mammals comprising the Ilonotremata. 

 Oenithoscelida (Gr. ornis, bird ; skelos, leg). Applied by Huxley to the 



Deinosaurian Reptiles, together with the genus Cowpsognathus, on account 



of the bird-like character of their hind-limbs. 

 OKTHOCERATiDiE (Gr. orthos, straight; keras, horn). A family of the Naii- 



tilidce, in which the shell is sti'aight, or nearly so. 

 Orthopteea (Gr. orthos, straight ; 'pteron, wing). An order of Insects. 

 OssicuLA (Lat. diminutive of os, bone). Literally small bones. Often used 



to designate any hard structures of small size, such as the calcareous plates 



in the integument of the Star-lishes. 

 OsTRACODA (Gr. ostrakon, a shell). An order of small Crustaceans which are 



enclosed in bivalve shells. 

 Otoliths (Gr. ous, ear; and litlios, stone). The calcareous bodies connected 



with the sense of hearing, even in its most rudimentary form. 

 Ovarian Vesicles or Capsules. The generative buds of the Scrtularida. 



Pachydermata (Gr. 2Mchus, thick ; derma, skin). An old Mammalian order 

 constituted by Cuvier for the reception of the Rhinoceros, Hippopotamus, 

 Elephant, &c. 



Palaeontology (Gr. palaios, ancient; onta, beings ; and logos, discourse). The 

 science of fossil remains or of extinct organised beings. 



Pal^otherid^ (Gr. palaios, ancient; thcr, beast). A group of Tertiary 

 Ungulates. 



Paleozoic (Gr. palaios, ancient ; and zoe, life). Applied to the oldest of the 

 great geological epochs. 



Palliobranchiata (Lat. pallium ; and Gr. bragchia, gill). An old name for 

 the BracMopoda, founded upon the belief that the system of tubes in the 

 mantle constituted the gills. 



Pallium (Lat. j-jaZZmyw, a cloak). The mantle of the Mollusca. Pallial : 

 relating to the mantle. Pallial line or impression : the line left in the dead 

 shell by the muscular margin of the mantle. Pallial shell : a shell which is 

 secreted by, or contained within, the mantle, such as the "bone" of the 

 Cuttle-fishes. 



Palpi (Lat. paljm, I touch). Processes supposed to be organs of touch, devel- 

 oped from certain of the oral appendages in Insects, Spiders, and Crustacea, 

 and from the sides of the mouth in the Acephalous Molluscs. 



Papilla (Lat. for nipple). A minute soft prominence. 



Paeapodia (Gr. para, beside ; podes, feet). The unarticulated lateral loco- 

 motive processes or "foot-tubercles " of many of the Annelida. 



Parietal (Lat. paries, a wall). Connected with the walls of a cavity or of the 

 body. 



Patagium (Lat. the border of a dress). Ajiplied to the expansion of the 

 integument by which Bats, Flying Sq^uirrels, and other animals support 

 themselves in the air. 



Patella. The knee-cap or knee-pan. A sesamoid bone developed in the 

 tendon of insertion of the great extensor muscles of the thigh. 



Pectinate (Lat. pectcn, a comb). Comb-like; applied to the gills of certain 

 Gasteropods, lience called Pectinihranchiata. 



Pectoral (Lat. pectus, chest). Connected with, or placed upon, the chest. 



