232 HENDRYj ON NAVICULA RHOMBOIDES, 



sented to observation upon several slides in my own posses- 

 sion, furnished through the kindness of Mr. Harrison, of 

 Hull, and others ; the first three slides representing the pro- 

 duce of Connecticut in America, and the fourth, that of 

 Lancashire, in England. 



I have on this occasion also, as heretofore, selected a com- 

 parative coarse striation in contrast to the high numbers so 

 usually assigned to this diatom on past authority, only won- 

 dering myself that when such great painstaking could have 

 been endured in searching, marking, measuring, and record- 

 ing fine delineations and high numerical quantities, that the 

 coarse, or lower measures, and bold developments should 

 appear never to have entered the field of the microscope or 

 to have attracted the attention of reputed acute observers, 

 even although the great mass of rhomboides partake of this 

 latter description, or are of low numerical value contrasted 

 with the assumed standard of 85 in '001 . 



A^. rhomboides. Slide I. — Connecticut (America). 



