170 Transactions of the Society. 



That however does not seem probable in the case of another 

 very strange rotifer, described and figured by Prof. Leidy in the 

 same paper, and which he discovered and described in 1857, 

 giving it the name of Didijoplwra. As the animal is attached 

 by a sucking disk, is almost motionless, very transparent, and 

 free from wrinkles, the rotatory organ would not have escaped 

 notice had it been present; yet neither Prof. Leidy nor Mr. 

 S. A. Forbes, who probably described the same creature under 

 the name of Cupelopagus hucinedax* could detect any vibratile 

 cilia. Prof. Leidy says that " Dictyojyhora is oval or ovoid, with 

 the narrower pole corresponding with the position of the mouth, 

 truncated, and it adheres by a small disk or sucker to one side of 

 the broader pole. . . From the truncated extremity of the body the 

 animal projects a capacious delicate membranous cup, forming more 

 than half a sphere, and more than half the size of the body. At 

 will the cup is entirely withdrawn into the body, and the orifice of 

 this becomes contracted and puckered into folds radiating from a 

 central point or orifice. . . The prehensile cup opens into a capacious 

 sac, which is within the body and occupies a good portion of its 

 upper half. The sac at bottom communicates with a mastax 

 nearly central in position. . . The mastax opens into a capacious 

 sacculated stomach. . . Numerous ova in all conditions, from the 

 earliest to those which contain fully developed embryos, occupy the 

 body-cavity of Bidyophora, sometimes in such numbers as to 

 obscure everything else from view." 



This most curious animal still retains some likeness to the 

 Floscules in spite of the degradation of so many parts. The 

 " membranous edging " of Aeydus has here developed at the 

 expense of the buccal funnel, which it has entirely supplanted, and 

 the peduncle has shrunk down to a mere sucking disk ; but the 

 " capacious sac," which lies between the mouth and the mastax, is 

 the exact counterpart of a Floscule's " crop " in which its food 

 accumulates after slipping down the tube hanging from the mouth, 

 and before passing the mastax into the stomach. On the other 

 hand the mastax with its five teeth in each jaw, and also indeed 

 the position of the sucking disk (which is on the side of the 

 ventral sm'face towards its lower end instead of at its extremity) 

 are decided points of difi"erence, to say nothing of the complete 

 absence of buccal funnel, lobes, setae, and vibratile cilia. 



Prof. Leidy quotes Cohn's remark that a rotifer without a 

 rotatory organ would be a " rude abnormity " (eine schroffe 

 Ahnormitdt) ; and indeed it does seem at first sight a very nice 

 question whether an animal that has no rotatory apparatus can be 

 a rotifer. Yet Stei^hanoceros and all the Floscules are pretty 

 nearly in this condition ; for their generally motionless setae have 



* See this Journal, ii. (1882) p. 625. 



