394 T. B. ROSSETER ON HYMENOLEPIS ACICULA SINUATA, 



uterine segments increase in size to 0*084 mm. in length and 

 1*056 mm. in breadth, which is their maximum width. On the 

 development of the six-hooked brood a radical change takes 

 place in the formative character of the proglottides, the segments 

 becoming longer and narrower — for example, 0*247 mm. in 

 length by 0-695 mm. in breadth, and 0*304 mm. by 0*810 mm. 

 The penultimate segment is barren, whilst the ultimate is nearly 

 a square (0*273 mm. by 0*378 mm.), and as this segment is not 

 rounded at its base I assume that segregation has taken place 

 (Figs. 2-9). 



The genital copulatory organs are unilateral in the segments. 



There is no genital cloaca, but the genital sinus is a cul-de-sac. 

 By this I intend it to be understood that there is no exterior 

 genital pore in the parenchymatous tissue of the hermaphroditic 

 segments (as is usual in the genus Taenia), for the purpose of 

 copulation. 



The male is anterior to the female, and both are contiguous. 



Throughout the strobila the male and female organs of 

 copulation, with a few exceptions, are from their inception situated 

 0*034 mm. from the lateral border. Some are situated farther 

 away than this, but the above is the rule, and in the exceptional 

 segments the genital organs — male and female — have not actually 

 pushed their way onwards through the tissue to the lateral 

 border. Both organs are developed side by side in the same 

 plane in the segment (about 6 mm. from the scolex), and in 

 their earliest stage appear as minute stellate bodies with rays 

 about 2 mm. in length. During their development they remain. 

 in contact until about 1 mm. farther down the strobila, when a 

 fission takes place. The male organ, in the form of a funnel 

 with an overlapping rim to its pore, and a long infundibulum 

 (a continuation of the ductus efferentia of the vesicula seminalis), 

 separates itself distally from the female. This act of fission is 

 not complete, the membranous tissue during separation being 

 arrested proximally at the periphery of both genital pores and 

 thus attaching them, the male posteriorly to the female 



