302 Tirms actions. — Botany. 



2. Aptogonum, Ehrenberg. 



A. undalatum, sp. iiov. 



Figures 1-4. 



The frond is filamentous, somewhat fragile, and without gelatinous 

 sheath. It is plane, or only very slightly twisted, and, as a rule, not long, 

 but with sometimes as many as fifty joints. 



Joints bi-crenate at the margins, and on the sides excavated so as to 

 leave between them an oval foramen. Viewed from below the length of 

 each joint is equal to the breadth. In the side view the height is rather 

 more than the breadth. Under- view quadrangular, the angles rounded, and 

 the foramen easily distinguishable. Upper view also quadrangular, but 

 across the foramen two projections are seen, one from each joint, meeting 

 at the centre. Side view quadrangular below, but curvate above, giving a 

 wavy appearance to the margin of the frond. The projecting processes are 

 seen in this view springing from the curve. The lower edge is bi-crenate. 

 End view quadrate below, with a projection at each of the lower angles, 

 convexo-triangular above, with a projection at the apex. In an emptyjoint 

 the median projecting process is visible. When slightly tilted, the end view 

 shows the quadrangular under-side with bi-crenate edge. Endochrome bright 

 green. Eays in end view inconspicuous. 



Not common. 



This plant seems to be intermediate between A. desmidium, Ehr., the 

 European species, and A. baileyi, the American species. In the former 

 the edges of the joints are bi-crenate, but there are no projecting processes 

 between them, and the end view is concavo- instead of convexo-triangular. 

 In the latter there are the projecting processes, but the edges are not crenate 

 but straight, and the end view (as given by Ealfs, Plate XXXV) shows a 

 rectilmear triangle, I find no mention also, in the descriptions of either of 

 these species, of the curvate appearance shown in the side view of my ^. 

 undulatum, which gives the peculiar wavy edge to the filament. In Dr. 

 Wallich's paper* on Desmidie® from Bengal, he figures A. baileyi clearly 

 without any undulating margin, though he shows the end view more convexo- 

 triangular than in Ealfs' figure. 



Length of joint (outside measurement), under or upper view, jsV^ inch. 

 Height of joint in side view, xxVo iiich. 



8. Sphserozosma^ Oorda. 



S. vertehratimi, Brebisson. (E. VI.) 



Not common. 



S. excavatuvi, Ealfs. (E. VI.) 



* " Annals of Nat. Hist.," 1860. 



