330 



HYALONEMA (OONEMA) HENSHAWI. 



Number 



Macramphidiscs 



30- 



20- 



10- 



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Fig. 20. — • Amphidiscs. 



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amphidiscs, which, as they are the largest forms, I name macramphidiscs. All 

 the other amphidiscs differ morphologically from these but are similar among 

 themselves. They can, as they comprise the small forms, be named micramphi- 

 discs. The part of the curve pertaining to these micramphidiscs is divided by 

 the deep depression at about 63.2 into two parts, one comprising the larger, 

 the other the smaller forms. Although the larger of these amphidiscs are very 

 similar morphologically to the smaller, there could, after their biometrical 

 study had pointed the way, be found certain morphological differences between 

 them, particularly in the curvature of the anchor-teeth, which corroborate their 

 biometrical distinction, and which, although slight, in my opinion justify a 

 division of the micramphidiscs into two subgroups : — large micramphidiscs 

 over 63.2 n in length, and small micramphidiscs under that. 



