Subclass of  Cestodes.

Cestodaria are monozoic hermaphroditic worms which are not subdivided and include only a single set of male and female reproductive organs (  Eucestoda/Fig. 2). Their  holdfast organs (if present at all) are not very well developed (  Amphilina foliacea/Fig. 1), but allow them to inhabit the intestine or the coelom of their hosts. In ontogenesis a 10-hooked  lycophora larva is involved. With respect to body organization and life cycles 2 orders can be distinguished:  Amphilinidea and  Gyrocotylidea (  Amphilina foliacea/Fig. 1,  Gyrocotyle/Fig. 1). Members of the Amphilinidea are parasitic in the coelom of sturgeons, other primitive fish, and tortoises, usually reaching a size of 2–8 cm (but up to 38 cm in species of Gigantolina). These ribbon-like monozoic and monoecius worms have their genital pores (vagina, male  cirrus) at the posterior end (  Amphilina foliacea/Fig. 1), but in the female the uterus opens at the anterior...