381] PSEU DOPEY LLIDEA FROM FISHES— COOPER 93 



PTYCHOBOTHRIIDAE Liihe 1902 



Scolex unarmed, with two separate and more or less strongly developed 

 bothria, or exceptionally replaced by a pseudoscolex. Neck absent. External 

 segmentation never absent, but frequently incomplete or obliterated thru 

 secondary foldings. Genital organs numerous, but only single in each proglot- 

 tis. Both surfaces of the chain of proglottides, apart from the genital openings 

 similar. Cirrus unarmed, with cleft cuticula. Opening of cirrus and vagina 

 behind the uterus opening, surficial or marginal, in the first case on the opposite 

 surface to the uterus-opening and almost median. No muscular bulb at the 

 inner end of the cirrus-sac. Receptaculum seminis, when present, has the 

 form of a small blind sac situated at the inner end of the vagina. Ovary and 

 shell-gland median. Testes in two lateral fields. Uterus never taking the 

 rosette shape, but usually forming a capacious undivided uterus-sac. Eggs 

 thin-shelled, without opercula; embryonic development in the uterus, and in 

 consequence of exhaustive production of eggs (but dependent on the time of 

 year in the case of many species) all the eggs of the whole tapeworm are at the 

 same stage of development. 



Sexually mature in the intestine of fishes; larval condition unknown. 



In his first diagnosis of the family Liihe (1902a:326) emphasized the similar- 

 ity of both surfaces of the strobila (in contradistinction to conditions in the 

 AcanthophaUidae), the unarmed cirrus with cleft cuticula, the peculiar cecal 

 receptaculum seminis and the absence of opercula in the eggs, but described 

 the uterus as follows: "Uterus nie die sogenannte Rosettenfonn annehmend, 

 wohl aber in der Regel eine geraumige Uterushohle bildend, welche die iibrigen 

 Genitalorgane, ohne dass freiUch deren Riickbildung eintritt, buchstablich an 

 die Wand drangen kann, indem die ganze Proglottis in reifen Proglottiden viel- 

 fach als ein einziger sackformiger Eibehalter mit verhaltnismassig sehr diinnen 

 Wandungen erscheint. " The uterus of Haplobothrium answers this descrip- 

 tion in that it is divided into a uterus-sac and uterine duct; but the remaining 

 reproductive organs are distinctly diphyllobothriidian in their nature. Con- 

 sequently, in order to differentiate more clearly the two families, Ptychoboth- 

 riidae and Diphyllobothriidae, and especially since the genus Haplobothrium 

 presents difficulties in this connection, it is necessary to know the developmen- 

 tal relationships between the uterine duct and the uterus-sac in those genera 

 in which they appear. Up to the present no adequate descriptions of the 

 latter have been published, so that here will be given the observations on the 

 development of the uterus to which reference was made above (p. 16), where 

 the conditions in Haplobothrium and Marsipometra were discussed. 



In Bothriocephalus scorpii the liunen of the uterus-sac appears suddenly 

 and with a diameter of 90^, the rudiment ahead showing as yet no signs of 

 forming a cavity. This enlargement is situated at first, however, in the cortical 

 parenchyma and among the longitudinal muscles, only the inner tip of the 



