to 750 long, 200 to 225 broad; The terminal segment, including the 

 mucro, 750 to 975 long, TOO broad; the mucro, or terminal cell, 170 

 long, 50 broad at base, tapering and sharp-pointed. 



The most remarkable feature of this Nitella is the swollen and thick- 

 ened nodes, both of stem and leaves. Owing apparently to this pecu- 

 liarity the various segments of the leaves drop off very early, the mucro 

 can be fonnd only on the youngest leaflets, the terminals of the leaves 

 drop from the node of the leaf, leaving three (usually) prominent and 

 thickened nodal cells (see Fig. 2), the leaves drop from the axis leaving 

 a ring of thickened nodal cells, as at Fig. 2 (hence the specific name), 

 these nodes persist on many of the older, almost naked stems, looking 

 like thickened nodes in some species of Polygoiuim. In the younger 

 parts of the plant the leaflets seem to tear off, leaving shreds of tissue 

 around the swollen nodal cell, (see Fig. 4), in which the leaflets have 

 dropped leaving a somewhat stipitate antheridium and a ring of tissue 

 of the base of the leaflet around each nodal cell. It would seem that as 

 the nodal cells thicken and enlarge the bases of the leaves become torn, 

 not inflating as the cells swell. The same peculiarity is found in the 

 sterile verticils, and it is rare to find a persistent crown of terminal 

 leaflets on a sterile leaf. 



The fruit is borne on the node of the leaf; the antheridium is 

 somewhat stipitate and persists after the subtending leaflets have fallen, 

 520 in diam. ; the oogonia, generally three in number at each node, 

 seem to arise on one side of the leaflet ; the coronula is evanescent ; the 

 oospore is nearly round, 280 long, 260 broad, with five striae, and is 

 minutely granular like that of N. Morongii, A. I have not been able 

 to observe whether the surface is or not covered with " felted fibres." 



This species was collected by Mr. Pringle in a " cold pool, Arroyo 

 Ancho, Sierra Madre, of W. Chihuahua, October 8, 1888," in Mexico. 



