On Asjolanchna Ebbesbornii. By Dr. Hudson. 627 



muscular network whicli is constantly compressing it into ever- 

 varying and graceful shapes. 



In the female the contractile vesicle appears to empty itself 

 into the broad end of the oviduct, but of this I am not certain ; in 

 the male there is a distinct narrow duct which opens into the same 

 cavity as does the penis. Moreover in the male there is obviously 

 a sphincter muscle between the vesicle and its duct; it is too 

 deHcate to be seen, but the frequent contraction of the duct at that 

 spot reveals its presence. 



The tortuous threads and vibratile tags that are so constantly 

 present in the rotifers are in this creature unusually large and 

 distinct. Fig. 18 gives an accurate drawing of one side of the 

 vascular system as seen in a male. The vibrating tags are often as 

 many as forty in number ; and they are evidently attached to a 

 delicate canal, which is itself supported by a twisted tube, whose 

 walls are delicately granulated and sometimes carry clear cells in 

 them, as seen in fig. 19. The posterior end of the tube on each side 

 opens on the contractile vesicle. I believe that the system is a depura- 

 tory one, and that the effete perivisceral fluid is drawn in through 

 the ciHated tags, and poured by the twisted tubes into the contractile 

 vesicle, to be by it expelled from the body. 



As to the structure of the tags themselves, it is clear from their 

 different appearances under different aspects that there cannot be 

 merely one large cilium waving in each tag. Dr. Moxon is pro* 

 bably right in considering the tags as having their inner surfaces 

 lined with extremely minute cilia, whose united action under 

 certain aspects produces the effect of one large vibrating cilium. 

 But the tags of A. Ebbesbornii are too small for such investigations, 

 and the subject is too long a one for further discussion in this 

 paper. 



Muscular System. — The arrangement of the muscles is very 

 similar to that of the majority of rotifers. Two large dorsal 

 muscles run nearly the whole length of the body, as do two 

 corresponding ventral ones ; while a third pair that may be called 

 lateral, lie close under the dorsal ones. All of these are attached to 

 the lobes of the head, and are branched there, having several points 

 of attachment. At their bases they are attached to the surface of 

 the cuticle by broad ends split into several fibres. 



Smaller muscular threads run from the head and are attached 

 half-way down to the dorsal and ventral surfaces ; while, from a spot 

 close to the mouth on the trochal disk, at least four pairs of trans- 

 verse muscles run to the edge of the trochal disk, and enable the 

 creature to rapidly draw it all together. 



The united pull of the six longitudinal muscles permits the 

 animal to withdraw its head with great rapidity, while the action 

 of these is counteracted by some half-dozen transverse muscles, which 



