38 PROCEEDINGS OF THE ACADEMY OF [1884. 



within reach. The raastax exactly resembles that of the three 

 other known species, being composed of two cftrved major unci, 

 near the base of each of which are situated four minor unci. After 

 beinor acted upon by the mastax, the food passes between the 

 unci into the oesophagus whence it is absorbed or thrown off by 

 the system. The ventral view of these organs is usually obscured 

 by large numbers of embryo, in various stages of development. 

 In front of the digestive sac, and apparently connected with it, 

 are two curved, pear-shaped sacs, of a transparent greenish hue. 



This rotifer, in common with all members of its genus, has 

 an unarticulated body, which is incapable of contraction. 



The net, which takes the place of rotatory organs, is shaped 

 like a hood, the ventral portion being elevated into an obtuse 

 lobe. In order to strengthen and support the long, curved, dorsal 

 outline of the net, there is, covering about two-thirds of it, a 

 membraneous shield, made doubly strong by two wide, arched, 

 muscular bands running around it. At the base of this shield is 

 a pointed projection, which is of still firmer composition. The 

 necessity for such an arrangement is obvious, when it is remem- 

 bered that the normal position of the animal is a semi-recumbent 

 one ; so that the weight of the net, which is about three-quarters 

 the area of the body, would be very considerable at these care- 

 fully strengthened points. 



The whole muscular system of this species is strongly marked 

 and powerful. Focussing downwards from the outside of the 

 dorsal view of the net, two gradually narrowing ridges or flaps 

 are seen extending up the inside of the hood. These flaps are 

 fringed with quite long cilia, and there are also shorter diagonal 

 lines of more minute cilia, the exact number of which lines could 

 not be accurately determined. This is the first instance in which 

 cilia have been discovered in any member of the genus, all 

 those species previously described, being stated to be totally des- 

 titute of these organs. In this case, their presence was first 

 detected while focussing through the dorsal side of the net, 

 although they could afterwards be plainly seen in a ventral view. 

 It was only by careful placing of the mirror that the cilia were 

 visible. 



Attached to the inside walls of the rotifer were the enigmatical 

 transparent bodies common in the Rotatoria ; and also a number 



