87 



On Amphipleura pellucida. 

 By Wm. HendrYj Esq.^ Surgeon^ Hull. 



Being favoured with the published results of Messrs. Sul- 

 livant and Wormley^s investigations on the subject of Nobert's 

 test-plate and the striae oi Amphipleura pellucida, and in sup- 

 port of my views heretofore advanced in the ^Microscopical 

 Journal' (July^ 1860) relative to a coarse striation of many of 

 these diatoms, I now transmit the measure of a series con- 

 tained in several slides in my present possession, as under; 

 having rejected every aspect of ambiguous character, and 

 exercised due care in the micrometer adjustment. 



I have selected purposely a comparative coarse striation, 

 in contrast to the high numbers promulgated by Mr. SoUitt, 

 whose 135 stripe in '001" said to be counted, and whose 

 175 in '001" reputed to be visible, are beyond my compre- 

 hension and experience ; at the same time I believe myself 

 prepared to compete in the exhibition of the finest visible 

 striation, using for my own part a -rjth objective made by 

 Dallmeyer, optician, of London. 



Slides. Strise. 



in '001" Amphipleura pellucida. 



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In the measurement of the above, as on all other occasions, 

 I have found it convenient to tabulate the adjustments of 



