DESCRIPTION OF BOTH RIO CEPHALUS LATUS. 685 



a deep longitudinal cleft between the usually curved or wavy lips. The 

 pi*oportion of the body occupied by the barren joints varies according to 

 the form of the worm. When the anterior portion of the body is much 

 thickened, one finds the first ripe ova 500 to 600 mm. behind the head, 

 in segments which are about 5 mm. broad and 2 mm. long, and which 

 are preceded by at least 600 immature proglottides. The number of eggs 

 is at first small, but it increases so greatly that the substance of the body 

 is not unfrequently raised up into a sort of vesicle. Pari passu with this 

 increase, the modification of the uterus progresses. It lies at first coiled 

 up in the middle of the joint, extending from behind forwards; but 

 afterwards, when a larger number of ova are collected, and when the 

 uterus has in consequence increased in length beyond the limits of the 

 joint, it is disposed in a loop-like fashion right and left. In this way 

 there is formed in the middle of the mature joints that peculiar stellate 

 or rosette-shaped figure, which has been compared to a flower (Linne) or 

 heraldic lily (Pallas), and has been from of old regarded as the most 

 striking characteristic of the species. The loops lie in close proximity to 

 one another, projecting towards the sides like the leaves of a rosette 

 (" horns "). There are generally four or five of these on each side, and 

 more rarely six. They are approximated to various degrees, according 

 to the state of contraction of the segments, but are always so grouped 

 that the anterior include the generative apertures between them. These 

 latter are surrounded by numerous papillce. The cirrhus- pouch opens 

 along with the closely adjacent vulva into a common transverse slit. The 

 opening of the uterus lies a short distance behind. The yolk-sacs are 

 embedded in the cortical layer of the lateral 

 regions, both ventrally and dorsally, are seen as 

 dark points through the otherwise almost trans- 

 parent parenchyma, and give the sides of the body 

 a yellowish grey appearance. The greatest de- 

 velopment of the uterus, which corresponds with the . FIG. 359. Eggs of Both- 



, -. 7.7 / .7 7 7 riocephalus latus : one of 



greatest breadth of the worm, does not, however, them after the liberation of 

 coincide with the limits of the middle portion, but the yolk contents, (x 300.) 

 is found at a considerable distance further lack. Stretches of joints 

 of some length, and not individual proglottides, are separated off, and 

 the line of division always passes through the anterior half of a joint. 

 The muscular layers are, on the whole, but slightly developed, and 

 calcareous corpuscles have only a scattered distribution throughout 

 the body. The eggs have an oval form, and average in diameter O'Oo 

 mm. and 0'035 mm. They are enveloped in a simple brown shell, pro- 

 vided with a lid with a distinctly defined margin. 



The larval form lives encapsuled in the pike, in the burbot (Lota 

 vulgaris), and probably in other river fishes. It rests let ween the muscles, 



