ROTIFERS. 219 



Rotifer makes long, quick, very sudden leaps, often 

 jumping so rapidly that it can hardly be seen ; it ap- 

 pears to spread the fins and disappear. Occasionally it 

 turns a complete somersault. The cilia are arranged in 

 a row along the front border. There is no foot. The 

 mastax is pear-shaped and large, but its structure is dif- 

 ficult to make out. The Rotifer has only one eye, 

 which is near the centre of the upper front surface. 

 The little creature has been called by some writers the 

 " sword-bearer," and is said to be quite common in some 

 localities, but I have never been fortunate enough to 

 find it. 



13. BBACHIONUS (Fig. 153). 



There are several species of this genus, all of which 

 may be known by the presence of a carapace with sev- 

 eral tooth-like projections or spines at the front, and 

 often also at the rear, by the two ciliary disks 

 and the single eye-spot. The species whose 

 empty carapace is shown in Fig. 153 is strict- 

 ly American. It is very attractive in its glass- 

 like transparency, active movements, and beau- 

 tiful carapace. It was discovered by Mr. H. 

 F. Atwood, of Rochester, and named Brach- 

 ionus conium by him.* It is quite common, and may 

 be easily recognized by the ten long teeth or spines 

 on the front border the central one on the upper side 

 or back being largest, and bent at a right angle and by 



* American Monthly Microscopical Journal, June, 1881. 



