694 GLOSSARY 



Autozooid. A feeding zooid in the Pennatulacea. 



Avicularium. A structure shaped like a bird's head attached to the zooecium 



in Bryozoa. 



Axial organ. A glandular organ in the axial sinus in echinoderms. 

 Axial sinus. An elongated sac alongside the stone canal in echinoderms. 



Basals. Calcareous interradial plates in the crinoid body. 



Bilateral symmetry. Having the right and the left sides alike. 



Bivalve^ A shell composed of two distinct and equivalent parts or valves. 



Bladder worm. The larval stage of tapeworms. 



Blastostyle. The reproductive polyp of a campanularian hydroid. 



Body-cavity. An internal space in the body in which lie the viscera. 



Body-wall. The outer portion of the body, which usually bounds the body- 

 cavity towards the inside. 



Brachial. Relating to the arms. 



Branchial. Eclating to the gills. 



Branchial heart. A lateral heart in the squid which receives blood from one 

 of the gills. 



Branchiate. Bearing gills. 



Branchiostegite. Paired lateral folds of the body-wall in crustaceans which 

 protect the gills. 



Brood-sac. A chamber in which the eggs develop in certain crustaceans. 



Brown body. A round mass in certain bryozoans resulting from the disinte- 

 gration of the soft parts of the body. 



Bud. An outgrowth of the body of an animal which becomes a new individual. 



Byssus. Cuticular threads secreted by the foot of many pelecypods and used 

 to attach the shell. 



CcBcum. A sac-like appendage of the digestive tract; a blind gut. 



Calamistrum. A comb of stiff hairs on the fourth leg in certain spiders used 

 by the animal to make a band of silk which stretches across the web. 



Calcareous. Formed of carbonate of lime. 



Callus. A thickening near the umbilicus in certain snail shells. 



Calyx. The body of a crinoid. 



Canal. A tubular prolongation of the lip of the aperture containing the siphon 

 in many snail shells. 



Carapace. The shell covering a portion or all of the cephalothorax in crus- 

 taceans. 



Cardinal teeth* The hinge teeth beneath the umbo in a bivalve shell. 



Carina. The median dorsal shell in barnacles. 



Cartilage. The internal portion of the ligament in certain bivalve shells. 



Cellulose. The woody cell-wall of plant cells and also of certain cells in the 

 tunic of tunicates. < 



Central teeth. In the radula of mollusks the central row of teeth. 



Centrodorsal. The basal portion of a non-sessile crinoid. 



Cephalic gland. A tubular organ at the anterior end of nemerteans. 



Cephalont. A sporozoon, when attached. 



Cephalothorax. A body-division formed by the fusion of the head and the 

 thorax in arthropods. 



Cerata. Dorsal projections in opisthobranchs. 



Ceratine. A horn-like substance forming the skeleton in certain corals. 



Cercariaj A larval form of trematodes. 



Cercus. A paired sensory projection at the posterior end in certain inverte- 

 brates. 



Cerebral tube. A sense organ of sipunculids. 



Chelate. Having forceps-like pincers. 



