WHEEL-ANIMALCULES. 197 



ends in a single point, or in several teeth when the part becomes 

 broad and indented in form of fingers. In other Rotatories the 

 jaws have the form of two stirrups, with the bases turned towards 

 each other, on which lie two or more teeth transversely, which 

 arise from the outermost arch l . 



[Where the oesophagus opens into the stomach, or lower down, 

 are two or more oval glandular pouches, which EHRENBERG com- 

 pared to the pancreas. The stomach is large and sacculated, and 

 in the saccules are large nucleated cells, or coeca are appended to 

 them. The cells and cosca are supposed to supply the office of a 

 liver. The intestine narrower, and of variable length, but generally 

 short, opens into a cloaca, of which the outlet is on the dorsal sur- 

 face at the extremity of the body. But sometimes the intestine 

 and anal outlet are wanting, and then the residue of digestion is 

 returned by the mouth 2 . The stomach and intestine are covered 

 with fine vibratile cilia. 



This description applies only to the females ; for, in the year 

 1849, the very interesting discovery of the male of Notommata 

 anglicawas made by BRIGHTWELL S of Norwich, and in it the entire 

 intestinal tract was absent ; there were neither pharynx, jaws, oeso- 

 phagus, nor digestive tube, and the mouth was closed. 



There is no circulating system. The nutrient fluid fills the 

 cavity of the body, and bathes all the contained organs. The re- 

 spiratory organ is supposed to be represented by tortuous tubes, 

 which are seen at each side of the body. A highly contractile 

 transparent vesicle opens into the cloaca, and from this vesicle the 

 tubes in question arise. To the tube on each side, minute pedi- 

 culated structures, various in number, with vibratile leaflets, are 

 attached. 



The female organs consist of an ovary situated under the diges- 

 tive tube, generally of an oval form, or like a horse-shoe, of which 

 the efferent duct opens into the cloaca. 



The ova are of two different kinds, summer- and winter- eggs, thin- or thick-shelled. 

 The summer-eggs are developed within the parent body, and the animal is then vivi 

 parous. The winter-eggs have been described by EHRENBERG, by HUXLEY, and by 

 LEYDIG, in many different species: their thicker external covering is granular, or 

 tuberculated, or beset with hairs. The winter-eggs are always laid, or are attached 



1 See EHRENBERG Zur Erkenntniss der Organisation in der Richtung des Jcleinsten 

 Raumes, Berlin, 1832, s. 46 51, Tab. IV. 



3 [DALRYMPLE Descript. of an Infusory Anim. allied to Notommata, Phil. Tram, 

 l8 49> P- 333-] 3 [Annals of Nat. Hist. Sept. 1848.] 



