Fig. 9

Proximal cystid muscles in the arachnidoidean Nolella(?) sp. a View of the proximal attachment side of cystids showing an enlarged base with distinct basal muscles. Volume rendering. b Similar such as found in (A) but different angle with cystid wall (blue) displayed with less transparency. Note the distinct swelling of the cystid base. Volume rendering. c Optical section through the enlarged cystid base showing the traverse of the basal muscle. d View of a cystid base with a thicker and more prominent peristomial tube. Note the lack of muscles in the wide cystid base. Volume rendering. e Lateral view of several zooids with thin peristomial tubes extending from the cystid base. Note that the left zooid is a developing bud. Abbreviations: az - autozooid, bm – basal muscle, cb – cystid base, cy – cystid appendage, da – developing autozooid, pc – pore complex, pt – peristomial tube, rm – retractor muscle