GLOSSARY 



395 



radii , lines proceeding from a common 



centre like the spokes of a wheel, 



86. 

 ramus, a branch or projecting process, 



131. 

 rictus, the corners of the month in 



birds, 315. 

 rostrum, beak, the frontal process of 



crustaceans. 



scansorial, capable of climbing, 315. 



scutellate, composed of plates, 315. 



scittellum, the third of the four pieces 

 composing the upper part of a tho- 

 racic segment of an insect, 59. 



septa, the radial calcareous plates of 

 a coral, 215. 



sinistral, left. 



siphon, the drawn-out edges of the 

 mantle folds of lamellibrauchs, 183; 

 the strand penetrating the chambers 

 of the Nautilus shell, also called 

 siphuncle, 173. 



spatulate, shaped like a spatula, or a 

 paddle. 



sphenotic, one of the bones forming 

 the ear capsule of fishes, 232. 



spinnerets, the tubercles through open- 

 ings in which the spider thread is 

 spun, 84. 



spiracle, one of the openings to the 

 air-tubes of insects, 59. 



spurious, not genuine. 



squame, a scale in decapods attached 

 to the antenna, 124. 



sternum, in vertebrates, the breast- 

 bone, 280; in insects, the ventral 

 part of a somite, 59. 



stigmata, spiracles. 



stock, colony, 207. 



stolon, a runner from which zooids 



bud, 220. 

 subopercular, the lowermost bone of 



the operculum in fishes, 232. 

 suborbital, a bone in fishes, lying 



below the eye, 232. 

 supraethmeoid, a bone of the nose in 



fishes, 232. 

 supraoccipital, a bone forming the 



upper part of the back of the head. 

 suture, a seam or structural line, 70. 

 symplectic, a bone uniting the quad- 

 rate to the bones suspending the 



lower jaw, 232. 



tarsus, the jointed foot of an arthro- 

 pod leg, 59. 



telson, the tail-piece of a crustacean, 

 11(5. 



tentacle, a projecting tactile organ. 



thoracic, pertaining to the thorax or 

 chest. 



tibia, the joint of an insect's leg next 

 above the tarsus, 59. 



trachea, one of the respiratory tubes 

 of insects, 64. 



trjchanter, a joint of the insect leg 

 lying distal to the coxa, 59. 



umbilicus, a depression in the centre 

 of the base of many spiral shells, 

 175. 



umbon.es, a protuberance just above 

 the hinge of a bivalve shell, 188. 



velum, a circular membrane extend- 

 ing like a shelf from the margin of 

 the jelly-fish bell, 211. 



viviparous, giving birth to well-de- 

 veloped progeny, 331. 



