1 2O GLOSSARY. 



Ra'cemose (L. racemosus, full of berries). A term applied to 

 the small glands in which the cells are arranged in clusters 

 round a central duct. 



Ra'chis (Gr. rachis, a spine, ridge). The stem of a fern frond ; 

 the shaft of a bird's feather. Also a cellular cord in the 

 Crinoidea. 



Radiale. A bone of the carpus which articulates with the 

 radius. 



Radia'lia (L. radius, a spoke, a ray). Radial pieces in the 

 calyx of the Crinoidea. Also the cartilages which radiate 

 from the basal pieces of the fins of the Elasmobranchii. 



Radia'ta (L. radius, a ray). According to Cuvier's system of 

 classification, one of the animal sub-kingdoms. 



Ra'dicle (L. radix, a root). The root of an embryo plant. 



Badiola'ria (L. radius, a ray). A group of the Protozoa. 



Ra'dius (L. a ray, a spoke). The outer bone of the ante- 

 brachium or fore-arm of the Vertebrata. A slender rod 

 articulated to each of the radial pieces of the oral skeleton 

 in the Echinidea. 



Ra'dula (L. a scraper). A part of the odontophore in the 

 Mollusca. 



Ra'mus (L. a branch). The name given to each half of the 

 lower jaw in the Vertebrata, and also to regions of the 

 ischium and pubis. 



Ra'phe (Gr. raphe, a seam). A term applied to a fine longi- 

 tudinal band of fibres running in the middle of the medulla 

 oblongata ; applied also to similar bands of fibres in the 

 Corpus callosum, and the Pons Varolii ; also to the ridge 

 separating the scrotum into two halves ; also to the median 

 furrow which runs along the dorsum of the tongue. 



Rapto res (L. raptor, pi. raptores, one who seizes, a robber). 

 According to the old system of classification, an order of 

 birds which included the birds of prey. 



Ratitae (L. rdtis, a ship without a keel). A division of the 

 class Aves, destitute of a keel to the sternum. 



Receptacula se'miuis (L. receptacles of the semen). Organs 

 in the earth-worms which receive the male reproductive 

 fluid. 



Recepta'culum chyli (L. receptacle or cistern of the chyle). 

 The dilated posterior extremity of the thoracic duct. 



