Five Neto Floscules, dec. By Dr. Hudson. Ill 



no sort of pretension to be considered as forming a rotatory organ, 

 and their vibratile cilia are so few and inconspicuous that their 

 loss alone would not be reason enough for removing these two 

 genera from among the rotifers. It is among the Notommata and 

 their allies that we find the most numerous instances of the degra- 

 dation of the trochal disk, especially among the parasitic species ; 

 and this, as might be expected, is often accompanied by the 

 degradation or loss of other characteristic organs, until at length 

 in Grosse's Taphrocampa we arrive at a larva-like creature destitute 

 aUke of gastric glands, vibratile tags, contractile vesicle, and trochal 

 disk ; its sole connection with the Eotifera being its characteristic 

 mastax. Prof. Leidy suggests that perhaps Tajplirocampa may 

 have a rotatory apparatus, which was concealed when Gosse 

 observed it, just as it was in the case of Lindia torulosa when 

 Dujardin discovered it. This of course is possible ; but even the 

 possession of such cihated appendages as those of Lindia would 

 leave Taphroeampa stripped of the greater part of a rotifer's 

 characteristics. 



In passing under review such a series of creatures as Lindia 

 torulosa, Albertia vermiculus, Noiommata WernecMi, Balatro 

 calvus, Seison Gruhei, and Taphrocampa annuJosa, it naturally 

 occurs to one that, in the case of animals departing so widely in other 

 respects from the rotiferous type, the further loss of a few vibratile 

 ciha would not seriously affect their classification ; but if Cohn 

 merely meant that it would be a "rude abnormity " for a rotifer to 

 possess aU the chief characteristics of its class, the mastax, 

 vibratile tags, contractile vesicle, &c., and yet lack a trochal disk, 

 he is certainly right ; for no such rotifer is as yet known. But 

 Prof. Leidy 's interesting discoveries make us acquainted with at 

 least two genera that are perilously near such an abnormal state of 

 things : for, although no mention is made of the contractile vesicle 

 and vibratile tags of Acyclus and DictyopTwra, it is obvious that 

 they may exist, as it would be at all times a very difficult thing 

 to see them. 



