359] PSEU DOPEY LLIDEA FROM FISHES— COOPER 71 



Nerve strands far towards the margins, dorsal to the cirrus-sac and vagina. 

 Testes in two lateral fields united ahead of and behind the uterus-sac and 

 central genital ducts. Vas deferens much coiled proximally, only weakly so 

 close to the cirrus-sac. Receptaculum seminis very long. Ovary reniform, 

 wings tubulolobular, isthmus thick. Shell-gland not in the middle of the 

 genital complex but towards the cloaca, ahead of the ovary. Vitelline follicles 

 numerous, not in two lateral fields but continuous from side to side in the 

 anterior and posterior regions of the proglottis, situated among the body 

 muscles. Uterus-sac pouched, occupying the whole of the medulla dorsoven- 

 trally but not transversely. Uterus opening towards the margin bearing the 

 genital cloaca. — ^apaLirlov a little pouch; /xrjTpa the uterus. 



Type species: M. hastata Linton. 



Attention is here called to the great similarity between Marsipometra and 

 Haplobothrium in that each is found in an isolated genus of fishes, respectively 

 Polyodon and Amia, which in turn are relegated to isolated famihes and orders. 

 As suggested previously by the writer (1914) in dealing with Haplobothrium, 

 the unique and generalized nature of these two genera is doubtless due to the 

 great age of their respective hosts. On account of the fact that it has a typical 

 bothriocephalid scolex, Marsipometra would seem to be the younger of the 

 two, for evidently a longer period of time must have been required for the 

 development of the peculiar trypanorhynchous scolex and method of segmen- 

 tation of Haplobothrium, if indeed both are not due to extreme degeneration 

 comparatively speaking. 



MARSIPOMETRA HASTATA (Linton 1898) 

 [Figs. 4, 5, 46, 47, 68, 83, 100, 101] 



Specific diagnosis: With the characters of the genus. Medium sized ces- 

 todes up to a length of 1 10mm. with a maximum breadth of 3mm. at the middle. 

 Scolex with deep bothria and prominent posterior borders, 1.5 to 2.8mm. 

 in length, 0.5 to 1.8mm. in width anteriorly and 1.3 to 2.0 posteriorly. Sub- 

 cylindrical neck, 0.8 to 1.5mm. wide. First segments very short and wide, 

 middle much broader than long and rectangular in outline, posterior ones 

 quadrate to slightly longer than broad. Whole strobila much depressed. 



Cuticula 5n in thickness, subcuticula 40 to 50^1. Calcareous bodies 18 

 by 13yu. Longitudinal musculature weakly developed, that of scolex strong. 

 Nerve strands 15 to 25 ^i in diameter. Four main excretory vessels in the 

 strobila. 



Genital cloaca 40 to 60/x in depth, at the middle of the margin of the proglot- 

 tis, irregularly alternating; hermaphroditic duct present, also sphincter cloacae. 

 Vagina opens immediately ahead of the cirrus. 



