HEXDRY^ ON THE HULL PLEUROSIGMA FASCIOLA. 153 



neighboiirliood of Hull, by George Norman, Esq., it is also 

 therein stated that Pleurosig ma fascial a is found at " Grimsby 

 much larger than on the north side of the Humber/^ 



I have also latterly, and since the gathering to which this 

 article chiefly relates, found the largest Fasciola at Stone 

 Ferry, near Hull. 



Relative Magnitude of the Large and Smaller Hull Fas- 

 ciola, magnified 483 diameters ; the outline taken by camera 

 hicida. 



Large Fasciola. 



Small Fasciola. 



The measures obtained of several diatoms of sizes under 

 consideration, are as follow : 



Hull recent Gathering. 



Slide 1. — Large and Small Variety. 



Full length of shell -yiT i^^h to -.^ and 



body -^ and -^ „ to -jJ^ and 

 Width of shell ttVs to ttVo „ in large variety 

 Transverse strise ... 52 in •001" „ ,, 



Longitudinal do. ... 35 in "001' ,, „ 



Number of strise in body, about 180 „ „ 



3 2 



1 

 o 



inch 



P.S 



Old usual Gathering. 



Slide 2. 



Full length of shell -^^^ of an inch 



body ^iy „ 



Width of shell tuVo }y 



Transverse strise 54 to 56 in 'OOl" 

 Longitudinal strise 66 m 'OOl" 

 Number of strise in body about 110 to 130. 

 -What is implied by the body is about the point of 



convergence of the exterior outlines ; otherwise the transverse 



