of Gastrotrichous Rotatoria. 217 



little, and appears to contain a small nucleus. These dilata- 

 tions appear at first like little spots of the cuticle, and the 

 latter consequently appears, under a sufficient magnifying- 

 power, to be punctate. 



The dorsal surface of the body is even. On the other hand, 

 its ventral surface has some small appendages, of a conical 

 form, whose position and number are always the same : all 

 show the same conformation ; they are cones formed by a 

 prolongation of the cuticle, and enclosing an axial cord, which 

 can be easily traced to the parenchyma of the body. This 

 cord is separated from its cuticular covering by a liquid or 

 semiliquid stratum. We find first of all six of these conical 

 appendages disposed in a half-ring a little behind the buccal 

 extremity ; the two outermost are the largest, and the tv\^o 

 innermost the smallest; the two intermediate ones have a 

 medium size. 



The following appendages are distributed in pairs on the 

 two sides of the body, but in such a manner that the first two- 

 fifths of its length are destitute of them. Between the two 

 hindermost appendages are placed eight others of smaller size, 

 in a transverse line. Lastly, there are two more placed near 

 the generative pore. In all the cones in the posterior part of 

 the body the axis appears to me to be double. 



All these appendages are moveable, and serve, no doubt, as 

 tactile organs, perhaps also as levers facilitating locomotion. 

 Those which form transverse ranges appear to be mutually 

 dependent, and move together like a comb. 



The cuticle also bears vibratile cilia, which appear to play 

 the principal part in locomotion when the animal is free : these 

 cilia are exclusively ventral ; they form a band which extends 

 from the foremost pair of conical appendages for almost two- 

 fifths of the total length of the animal. At this point, which 

 is exactly at the level of the union of the oesophagus and in- 

 testine, the ciliated band stops abruptly; behind there are 

 no vibratile cilia. The Hemidasyesj therefore, properly speak- 

 ing, are Thoracotricha rather than properly Gastrotricha. 



The anterior extremity is separated from the rest of the 

 body by a slight constriction at the level of the anterior pair 

 of ventral appendages. This part may be designated by the 

 name of cephalic hhe^ although, leaving the mouth out of con- 

 sideration, it presents nothing which could characterize a head. 

 This lobe is covered with slender and stiff bristles, like the 

 tactile bristles of the MoUusca, Annelides, and Turbellaria, 

 and in particular those of the other Gastrotricha. The 

 mouth is terminal, surrounded by a circular lip broken up into 

 little obtuse papillae and covered with vibratile cilia. It leads 



