20 
15 
10 
5 
HYALONEMA (PRIONEMA) CRASSUM. 
281 
fall into two groups, large and small ones. These two groups are very clearly 
distinguished, there being no amphidiscs 62-159 n long. This absence of inter- 
mediate amphidiscs finds its expression in the adjoined graph in the large gap of 
the curve between 72.89 and 129.13. The amphidiscs the lengths of which are 
represented by the curves to the right of the gap belong to the morphological 
groups 1 and 2. The two curves overlap considerably. The amphidiscs to 
Smooth y Macramphidiscs. 
Serrated J 
Micramphidiscs 
which the curve to the left of the gap pertains are those of the morphological 
groups 3 and 4. There is a conspicuous depression in this curve at 37.40- 
41.14, corresponding to the absence of amphidiscs 37-41 m long. This depres- 
sion may be taken as the limit dividing the (smaller) amphidiscs of the mor- 
phological group 4 from the larger ones of group 3. 
