VI 



Marginal (or oral) spines. S])iiu's issiiiiif^ i'roni llic iniuT niarfiin of a f^yiiinocyst. In 

 viTv rare cases fCri'piddcantlia Poissoni, Mcudporu hyulinaj they are found together with a 

 strongly ik-vcloiu'd frontal cryptoeysl. 



Acropetalous spines. Spines issuing from Ihe cirtunilVrence ol a pore (pseucloporu). 



Bilaminate spines. Spines (generally Hat) the inner layer of which is formed by a 

 cryptocyst while the outer layer is formed l)y a gymnocysl. They are only found in the 

 family Cnlcimriidae and reach their greatest development in the genus Coslicclla. 



Lateral chambers. Bryozoids generally developed as kenozooecia, found as a rule in 

 a number of four on each side of an internode in the family Calcnariitlae. 



Simple operculum. A wcll-chitinized or calcified separable operculum the hing-line of 

 wMch stretches between the two proximal corners and as a rule coincides with the 

 proximal edge of the aperture. 



Compound operculum. A well-chitinized separable operculum, the hinge-line of which 

 is placed distally to the proximal edge. Only the distal part of it corresponds to an oper- 

 cular valve or a simple operculum. In the Ascophora the proximal part of it, the »accesso- 

 rial part«, serves as operculum to the compensation-sac. 



Peristome. A calcareous projection more or less completely surrounding the aper- 

 ture of the zooecium. The entrance to this, often tubular, |)rojeclion is the "secondary 

 aperturcK. 



Ooecium (= ovicell). A more or less calcified marsupium placed near the zoa?cial 

 aperture, into which the eggs pass from the zottcium in order to be develo])ed into 

 larva. 



Endozooecial ooecia. Internal ooecia consisting of an endooa'cium formed by the distal 

 wall and of an cctoo(ecium formed by the covering membrane. 



Hyperstomial ocecia. External two-layered ooecia, consisting of an cndoocecium and a 

 more or less developed ectoooecium. 



Perlstomial ooecia. Single-layered oa'cia formed by the peristome. They are found in 

 the families Tubucellariidae and Lckylhoporidac and perhaps also the oojcia of the families 

 Conescliarcttinidae anil Holoporellidae may be referred to this division. 



Endotoichal ooecia. Hollows formed by resorption in a thick calcareous frontal wall 

 and at last opening outwards. They are found in the families Cellulariidac, Membranicella- 

 riidac and Setosellidae. 



Acanthostegous ooecia. Marsupial spaces lying between the covering membrane and 

 two series of concurrent spines. They are found in Electro zostericola and El. (Heterocecium) 

 amplectens. 



Double-valved ooecia. Oa?cia consisting of two arched hollow valves (kenozooecia). 

 They are found in Algsidium parasiticum. 



Basal mark. A curve seen on the basal surface of a hy|)erstomial ofecium, circum- 

 scribing that part of the frontal wall of the zoa'cium, which takes jiart in the formation 

 of the endoocEcium's basal wall. 



Basal. The surface with which an incrusting colony is fixed and the corresponding 

 surface in a freely growing colony. 



Frontal. The surface opposite to the basal and that in which as a rule the aperture 

 is placed. Sometimes, however, the aperture may be terminal, viz., ))laced in the ti]) of Ihe 

 zooecium. 



