264 



HYALONEMA (PRIONEMA) AGUJANUM. 



The rare large micramphidiscs have a stout shaft with an exceptionally 

 large, usually somewhat irregular, central tyle. This tyle bears numerous 

 minute and slender spines. These are not arranged in a verticillate manner, 

 but are scattered over the whole tyle. The remaining parts of the shaft also 

 bear minute spines. The anchor-teeth, which arise nearly vertically from the 

 end of the shaft, are curved quite uniformly throughout, through an angle of 

 about 90°, so that their end-parts are nearly parallel. The dimensions of these 

 amphidiscs are : — 



LARGE MICRAMPHIDISCS. 



The small micramphidiscs (Plate 75, figs. 24-27, 31-34; Plate 77, fig. 8) 

 have a straight shaft, which is either simple, cylindrical, and without any trace 

 of a central tyle, or, more rarely, slightly thickened at or near the centre to a 

 small central tyle. Such central tyles on the shaft are much more frequent in 

 the small micramphidiscs of var. lata than in those of var. tenuis. The shaft is 

 covered throughout with more or fewer, sometimes very numerous minute spines. 



' Only two seen. 



