6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



there is no clear line of demarcation between the A and B forms. 

 Both forms occur on different regions of the same colony with a region 

 of transition between them. 



Figures S-7. — Victorella argilla, schematic drawings (parietal muscles, retractor muscles, 

 and testes omitted): S, distal end of a form B zooid; 6, form A zooid, frontal view; 7, 

 schematic median saggital section of a form A zooid. (Abbreviations: app = apertural 

 papilla, cae = caecum, csp = central sphincter of three, dia = diaphragm, fpr=fiIiform 

 process, mus = apertural muscles, ova = ovary, sep = septum, set=setigerous collar, 

 sph = sphincter muscle of form A, tub = connecting tubule.) 



Form B 



ZoARiuM. — Foreign material in the form of siliceous sediment and 

 detritus is extensively integrated into the mature colony of form B. 

 The relative quantity of nonoxidizable inorganic material can be 



