Fig. 20. Amphlroa canaliculata Mart, 

 A diagramatic figure of a cross section of an articulus. Compare the 

 ribs, depressions and canaliculations in 28, 24, 25 and 2(3. In Amp. 

 pusslla the dorsal surface is costated, while in the others the ventral 

 is much more costated : in A7)ip. misakiensis it is canaliculated in 

 the dorsal while in Amp. canaliadata in the ventral side. 



Figs. 27 — 28. Ampliiroa crass Issima. 

 Diagramatic figures of the cross sections of the articuH. x Ca. 7. 



Fig. 29. Amphiroa declinata. 

 A diagramatic figure of a cross section of an articulus. x Ca. 7. Compare 

 27, 28 and 29 ; also observe that the conceptacles are projecting 

 obliquely toward the ventral side. 



