ROT1FERA. 



405 



world, observed them in the north of Africa 

 and the north of Asia ; they are commonly 

 distributed throughout Europe. The loca- 

 lities they inhabit are very various, some are 

 found in fresh water, other in salt. They are 

 fond of confervse, and may be easily found 

 nestling among these plants. They some- 

 times are in great numbers, so that they dis- 

 colour the waters in which they exist. The 

 species of Triarthra give a milky opaque- 

 ness to the water in which they are found. 

 The species of Polyarthra are interesting on 

 account of the finlike organs which are de- 

 veloped at their sides, and by which they are 

 able to move about. Several of the Notom- 

 mata are parasitic on other animals, and thus 

 approach in habit some of the higher epizoa. 

 The elongated seta3 or bristles of the species of 

 Triarthra are also worthy of notice (fig. 297.). 



Family 6. EUCHLANIDOTA. Character. 

 Loricated Rotifers, with a many-parted ro- 

 tatory organ. 



All the species of this family are clothed 

 with a lorica, which resembles the exoskeleton 

 of tortoises or crabs. Many of the species 



are remarkable for the appendages of the 

 shield, as setce in Euchlanis and Stephanops, 

 hooks (uncini) in Colurus, horns (cornicula) in 

 Dinocharis, spurs or respiratory tubes (calcar 

 sipho) in Euchlanis (fig. 294*.) and Salpina, a 

 helmet (cucullvs), in Stephanops. Most of the 

 species have a furcated foot, some few of 

 them have styliform feet. The interior of 

 these animals is not so well observed as in 

 families where the shield is of a less dense 

 character. A muscular system, consisting of 

 both longitudinal and transverse fibres, and 

 muscles to move the foot, can be seen in most 

 species. The nutritive organs consist of a 

 muscular oesophageal head, furnished with two 

 jaws bearing teeth. The oesophagus is mostly 

 a short tube. In eight genera the alimentary 

 canal assumes a conical form, in the re- 

 mainder it is constricted into a gastric organ. 

 Two round or egg-shaped intestinal glands 

 are present in all the species. The anal orifice 

 is situated at the back of the basis of the 

 foot (fig. 302. a). An ovarium with small ova, 

 in four genera, Euchlanis, Monostyla, Stepha- 

 nops, and Squamella, are seen, in the form of 



Fig. 294. 



Euchlanis triquetra. 

 a, single eye ; b, band of muscles with transverse striae ; c, 



d, alimentary canal. 

 D D 3 



