6 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



with powerful muscles to operate the mandible. They are sometimes 

 vestigial. 



Hyperstomial. Referring to external ovicells. These are often more or 

 less embedded in the g>'mnocyst of the succeeding zooecium but careful 

 dissection will show that they arise above the distal wall of the zooecium 

 to which they belong. 



Hypostege. A cavity between the ectocyst (frontal membrane) and 

 the cryptocyst in the Anasca, the hydrostatic chamber. 



Kenozooecium. A member of the colony in which there is no polypide 

 and usually no aperture, such as the stalk segments of CaulibugulCj the 

 internodes of radicles, etc. 



Lacunae. Pores between the costae of the cribrimorphs. 



Lumen. A clear line or pore on the middle of a costule in the cribri- 

 morphs. 



Lucida. A clear area in a chitinized membrane such as the operculum 

 or mandible. 



Mandible. The chitinous movable part of an avicularium; it is ho- 

 mologous with the operculum of a zooecium. 



Mural rim. The frontal edge of the side walls, often bearing spines in 

 the Anasca. 



Onychocellarium. An avicularium in which the mandible has lateral 

 membranous expansions (winged). 



Ooecium. Any structure containing the larva during its development ; 

 it may be either hyperstomial or endozooecial. 



Operculum. A chitinous membrane which closes the aperture like a 

 trap-door in the Cheilostomata. In the Anasca it is connected proximally 

 with the frontal membrane. 



Opesia. The large orifice beneath the frontal membrane of Anasca; 

 often occupying nearly all of the frontal area. 



Opesiule. A small perforation or notch in the cryptocj^st for the pas- 

 sage of muscles to the ectocyst in Coilostega (e.g. Thalamoporella) . 



Ovicell. The same as Ooecium. 



Pedunculate. Elevated on a stalk or pedicel, referring usually to 

 avicularia. 



Pericyst. A calcified frontal above the ectocyst in certain Anasca, usu- 

 ally formed by the fusion of marginal spines. 



Peristome. An elevated rim around the aperture. 



Polypide. That part of the individual freely movable within the body 

 wall and including the tentacles and intestinal tract. 



Pore chamber. See Dietellae. 



