116 DESMIDS OF THE UNITED STATES. 



acute point and the other into an acutely bidentate apex ; ends 

 rounded or emarginate. 

 Diameter 160-212 ;t. 



This species made its first appearance from Brazil and was 

 described by Nordstedt in 1869 in a scientific journal of 

 Sweden. Wood gave the same plant a new name a few years 

 later. The former has a claim of priority hence should 

 stand. The plant varies considerably in size, and in the form 

 of the terminal lobes ; some are more rounded than others. 



It has been found in a large number of States. 



M. os( itans. Ralfs. Plate XXXIII. figs. 3, 4. 



Cells of nearly equal length and breadth ; the end lobe 

 separated from the adjoining lube bya rounded or acute-angled 

 sinus; lobes horizontal, conical, their extremities usually 



bidentate. < )ne form has the ends dt' the terminal lobe acute. 

 The end lube- are much shorter and narrower than the others. 

 Transverse view fusiform ; membrane punctate. 

 Diameter 150-160 />. 



Bailey report- this species from Florida and Rhode Island, 

 but make- the measures much less. I have specimens from 

 Florida, Massachusetts and New Jersey. They were of the 

 given measures. 



M. pinnatifida, (Kg.) Half-. Plate XXXVII, figs. 7, 8, 9. 



Ends straight ; semicells deeply constricted, lobes horizontal, 

 more or less fusiform with apices bidentate. 

 Diameter varies from 83110 u. 



Somewhat like the preceding, but very much smaller, and 

 lobes not so swollen. 



Much more frequent than M. oseitans. 



Some are found with the basal lobe wide 'fig. 9) these I 

 have named, 



Var. INF LATA. 



M. KITCHF.LII. Wolle. Plate XXXVII. tig-. 1,2. 



Cells about as long as wide, sinus separating the semicells 

 an acute angle, ampliated ; basal lobe- suboonically produced, 

 obliquely and broadly truncate with the two angles drawn out 

 into somewhat diverging processes, furcate at the ends; a 

 rounded sinus between ; polar lobe separated from the basal 



