GLOSSARY. 813 



RADIATA (Lat. radius, a ray). Formerly applied to a large number of animals 

 which are now placed in separate sub-kingdoms (e.g., the Ccelenterata, the 

 Echinodermata, the Infusoria, &c.). 



RADIOLARIA (Lat. radius, a ray). A division of Protozoa. 



RADIUS (Lat. a spoke or ray). The innermost of the two bones of the fore- 

 arm of the higher Vertebrates. It carries the thumb, when present, and 

 corresponds with the tibia of the hind-limb. 



RADULA (Lat. radula, a scraping-iron). An epithet often given to the toothed 

 lingual ribbon or " odontophore " of the higher Mollusca. 



RAMUS (Lat. a branch). Applied to each half or branch of the lower jaw or 

 mandible of Vertebrates. 



RAPTORES (Lat. rapto, I plunder). The order of the Birds of Prey. 



RASORES (Lat. rado, I scratch). The order of the Scratching Birds (Fowls, 

 Pigeons, &c.). 



RATITJS (Lat. rates, a raft). Applied by Huxley to the Cursorial Birds, 

 which do not fly, and have therefore a raft-like sternum without any median 

 keel. 



RECTUM (Lat. rectus, straight). The terminal portion of the intestinal canal, 

 opening at the surface of the body at the anus. 



REPTILIA (Lat. repto, I crawl). The class of the Vertebrata comprising the 

 Tortoises, Snakes, Lizards, Crocodiles, &c. 



RETICULOSA (Lat. reticulum, a net). Employed by Dr Carpenter to designate 

 those Protozoa, such as the Foraminifera, in which the pseudopodia run 

 into one another and form a network. 



RETICULUM (Lat. a net). The second division of the complex stomach of 

 Ruminants, often called the "honeycomb-bag." 



REVERSED. Applied to spiral univalves, in which the direction of the spiral 

 is the reverse of the normal i.e., sinistral. 



RHABDOPHORA (Gr. rhabdos, a rod ; and phew, I carry). Employed by Prof. 

 Allman as a name for the Graptolites, in consequence of their commonly 

 possessing a chitinous rod or axis supporting the perisarc. 



RHIZOPHAGA (Gr. rhiza, root ; phago, I eat). A group of the Marsupials. 



RHIZOPODA (Gr. rhiza, a root ; andpous, foot). The division of Protozoa com- 

 prising all those which are capable of emitting pseudopodia. 



RHOPALOCERA (Gr. rhopalon, club; keras, horn). A name given to the But- 

 terflies among the Lepidoptera in allusion to the fact that the antennae are 

 clubbed at the end. 



RHYNCHOLITES (Gr. rhunchos, beak ; and lithos, stone). Beak-shaped fossils, 

 consisting of the mandibles of Cephalopoda. 



RODENTIA (Lat. rodo, I gnaw). An order of the Mammals ; often called Glires 

 (Lat. glis, a dormouse). 



ROSTRUM (Lat. rostrum, beak). The "beak" or suctorial organ formed by 

 the appendages of the mouth in certain insects. 



ROTATORIA ( = Rotifera). 



ROTIFERA (Lat. rota, wheel ; and fero, I carry). A class of the Scolecida 

 (Annuloida) characterised by a ciliated "trochal disc." 



RUGOSA (Lat. rugosus, wrinkled). An order of Corals. 



RUMEN (Lat. the throat). The first cavity of the complex stomach of Rumi- 

 nants ; often called the " paunch." 



RUMINANTIA (Lat. ruminor, I chew the cud). The group of Hoofed Quadru- 

 peds (Ungulata) which "ruminate" or chew the cud. 



SACRUM. The vertebrae (usually anchylosed) which unite with the haunch- 

 bones (ilia) to form the pelvis. 



SAND-CANAL (= STONE-CANAL). The tube by which water is conveyed from 

 the exterior to the ambulacral system of the Echinodermata. 



SARCODE (Gr. sarx, flesh ; eidos, form). The jelly-like substance of which 

 the bodies of the Protozoa are composed. It is an albuminous body con- 

 taining oil-granules, and is identical with protoplasm. 



SARCOIDS (Gr. sarx; and eidos, form). The separate amcebiform particles 

 which in the aggregate make up the " flesh " of a Sponge. 



SAURJA (Gr. saura, a lizard). Any lizard-like Reptile is often spoken of as a 



