Fig. 12 in Boring bryozoans: an investigation into the endolithic bryozoan family Penetrantiidae

Fig. 12 Histological semi thin sections of the opercula of five different penetrantiids. a Penetrantia concharum from Sweden. b P.cf. concharum from France. c P. parva from northern New Zealand. d–e P. parva from southern New Zealand. Asterisk marks the opercular pit on the frontal side. f P. irregularis from southern New Zealand. g P. clionoides from Guam. bc body cavity, c collar, op operculum, opg opercular groove, t tentacle, ts tentacle sheath, v vestibulum