276 EVEXLNGS AT THE MICROSCOPE. 



This spine probably represents not tlie foot, but one ol 

 the toes at the end of the foot. For it is attached to a 

 very short foot, in the midst of two or three bract-like 

 spines, one of which, longer than the rest, and distinct- 

 ly movable, probably represents the other toe undevel- 

 oped. The long spine is set on by a proper joint, a 

 globose bulb being inserted into a socket, which allows 

 it free motion, in all directions except backward. The 

 socket itself is contained in a second joint, the basal 

 part of which is inserted at some distance within the 

 aperture of the lorica. Tliis articulation is formed by 

 an infolding of the skin, but is permanent in its po- 

 sition. 



The most remarkable circumstance connected with 

 this elegant little animal is the unusual form of the 

 dental apparatus, which differs so immensely from that 

 of Bvachionus^ that we should never recognise them as 

 being the same organs, if we had not numerous inter- 

 mediate links, which by insensible gradations connect 

 the two remote forms. 



The mastax is a somewhat slender sac, much pro- 

 duced in length, and with the component lobes greatly 

 and irregularly developed. The incus has a fulcrum 

 of great length and slenderness, a straight rod with a 

 dilated foot. The rami are small, and pincer-shaped, 

 but with the angles greatly produced. The mallei have 

 long, slender, incurved maniibria^ and simple unci. 



But the remarkable circumstance is the non-sym- 

 metrical character of tlie apparatus. Tlie left side is 

 much more developed than the right. Tlie left angle 

 of the incus descends to a greater distance than the 

 right ; and its extremity is dilated into an expansion, 

 with several irregular points, to which muscular threads 



