1899] 



MICROSCOPICAL JOURNAL. 



191 



inside view of fig. 1, which being similar to it renders 

 another figure unnessary. 



Turning now to a P. angulatum, we have in the out- 

 side view at fig. 5 the extremeties of the pipes very dif- 

 ferently arranged. Here we see the left-hand pipe slight- 

 ly bent down, while the right hand one is considerably 

 turned to one side. Passing on to an inside view, fig. 6, 

 we also find a totally different structure : the nodule has 

 become oval, with the raphes pipes running a little way 



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11 



10 



into it at each extremity. Focussing down, we come to 

 the inside view of fig. 5, there being no intermediate im- 

 age, as was the case in the fossil form. 



In figure 10, the ends of the raphffi pipes of a Notting- 

 ham Pleurosigma are shown greatly magnified, and it will 

 be seen that one side exhibits a tendency to turn down, 

 this slight displacement, being just perceptible. Care 

 must be exercised always to examine a specimen that is 



