102 M. L. Plate on Ecfojiarosi'tic Botatoria 



surface and here forms a second coiled portion, which is fur- 

 nished with a third flicker-organ (fig. 13, s*). From this 

 point it acquires a more considerable diameter, about five 

 times as great as before, and in the male runs obliquely 

 backwards and upwards to the posterior end of the sexual 

 apparatus. As to the mode in which it unites with the latter 

 organ, I have unfortunately no precise information. The 

 aquiferous vessel seemed to me to open into the seminal 

 vesicle, or a little before this into the testicular duct (fig. 13). 

 In the female the secretion-canal only rises a little towards 

 the back, and then runs backwards close and parallel to the 

 stomach, opening into the efferent duct, which is common 

 to both ovaries. Soon after this wide aquiferous vessel 

 on each side has quitted the coiled-up portion situated at the 

 commencement of the trunk, it emits, in both sexes, a slender 

 lateral branch which runs backward along the ventral 

 side of the animal (fig. 13, to.g^), the lumen of which is 

 not wider than that of the canal in the neck. At the point 

 of passage of the trunk into the tail this branch forms a 

 third coil lying close to the ventral side and connected 

 with two further flicker-organs (fig. 13, .s*, z^). In some 

 Asplanchnce, the aquiferous vessels of which also fork, the 

 branches unite again before opening into the contractile 

 vesicle, and thus form a loop. I therefore supposed that 

 in Paraseison also there might be present a tubercle issuing 

 from the hindmost looping and returning to the main canal ; 

 but this was not to be found, and consequently the canal w.g^ 

 seems to terminate crecally here. The five flicker-organs 

 on the right and left sides which appear to be proper to Fara- 

 seison show no remarkable peculiarities in their structure. 

 They are small, cylindrical, posteriorly closed tubules, with a 

 cilium vibrating within them ; a broad, superficial, and narrow 

 edge- view, such as we meet with in so many other Rotatoria, 

 is not distinguishable here. The wide main canal of the 

 trunk has only a narrow lumen, but a thick wall charged with 

 many granules and vacuoles. Frequently the fluid-vesicles 

 lie close behind one another, like the beads in a necklace. 

 The same finely granular, gland- like constitution occurs also 

 in the coiled parts ; while the narrow canals in the head, neck, 

 and trunk are clothed with a delicate almost structureless 

 membrane. 



The structure of the secretory apparatus described above is 

 interesting, because it deviates from the typical construction 

 of this organ by the want of a contractile vesicle and by the 

 development of particular parts into mere conveying-ducts and 

 of others into secretory divisions ] at least it appears to me 



