120 DESMIDS OF THE UNITED STATES. 



'.."> //.: length 110 //.. of specimens from Florida; 

 diameter 125-150 ^. ; length 155-105 yw., of New Jersey 

 specimens. 



This species appears to be related to M. rnitinxn. var. /-nata t 

 Nord., but is smaller ; the lobes are not so deeply, nor so often 

 intersected, and the polar lobe is more exserted and more 

 dilated at the end. 



M. PAPILLIFEEA, Breb. Plate XXXVIII. figs. 8, 9. 



Orbicular, with marginal gland-like teeth ; semi-cells five 

 lobed; lateral lobes dichotomously incised ; incisions narrow 

 linear, the principal sinuses bordered by a row of minute 

 granules. The end lobe about as wide as the others, and 

 ernarginate, its angles dentate. Endochrome is usually yel- 

 lowish or brownish green. 



Diameter 95-112 p. 



Is found sparsely in shallow pools, but in a wide range of 

 many States. 



M. ROTATA, (Grev.), Ealfs. Plate XXXVIII, figs. 1, 2, 3. 



Orbicular, smooth ; semi -cells five lobed ; lobes dichoto- 

 mously incised with ultimate subdivisions variously biden- 

 tate in different plants. End lobe somewhat exserted. The 

 basal lobes have each four subdivisions, and the intermediate 

 lobes each eight. 

 Diameter 200-250 p. 



M. DENTICULATA, (Breb. \ Ralfs. Plate XXXVIII, figs. 4-8. 



Near the preceding, but separated by the usually obtuse 

 apices of the subdivision, often more oval form of cells, and 

 equal number of subdivisions in the basal and intermediate 

 lobes; polar lobe not exserted. Size about the same, but 

 many smaller varieties. Common. 



M. VERRUCOSA, Roy. Plate XLVII, fig. 10. 



In outline this species agrees with smaller forms of M. 

 denticulata, Ralfs, but differs from these and other described 

 forms by the remarkable row of creuulated, circular or oval 

 basal inflations, crossing from side to side, larger towards 

 the center, gradually growing smaller towards the margins. 



The original type was found in Scotland. The first from 

 this country is from a pond near Minneapolis, Minnesota, in 

 collections made by Miss E. Butler. 



