style subdorsal, directed outward, scarcely prominent ; keel not reaching to style, very 

 broad and flat, causing the nut to be subtriangular in section ; endocarp hard and thick, 

 sculpture coarse irregular cells. 



Length 2.4 mm., breadth 1.6 mm., thickness 1.5 mm. Brunssum. 



Of this species we have seen 4 nuts, all from Brunssum. The unusual thickness 

 of the nut in proportion to its breadth causes the fossils to be compressed irregularly, 

 or from back to front, not laterally as in most species. 



POTAMOGETON Sp. 6. 

 PI. II, fig. 6. 



Nut broadly ovate sometimes almost orbicular somewhat compressed, with large 

 deep central depression, ventral margin convex above concave below the long spine, 

 dorsal margin gibbous, attachment lateral; style sub4ateral erect long, conical at base 

 slender above; keel flat and crested, reaching to the style, with about 7 long thin spines; 

 endocarp moderately thick, with a long thin spine on either side of the base, sculpture 

 coarse irregular cells and rugosities. 



Length 2.7 mm., breadth 2 mm. Swalmen. 



These nuts agree closely in size, shape, and general characters with P. tuberculatus ; 

 but the spines are so very distinct that we cannot include it in the living species. The 

 spines in our fossil are long, slender, and arranged in a single row. In P. tuberculatus 

 instead of this single row there is a band of short tubercles. Also, in our fossil the en* 

 docarp has two long spines at the base ; in P. tuberculatus these are very short and 

 scarcely more than tubercles. 



POTAMOGETON Sp. 7. 

 PI. II, fig. 7. 



Nut obovate somewhat inflated, with large central depression, ventral margin 

 convex and prominent above concave below, dorsal margin semicircular, attachment 

 basi*lateral; style apical short and conical; keel somewhat crested, continued into the 

 style, with a few obscure tubercles down the middle ; endocarp fairly hard, sculpture 

 irregular hexagonal pits. 



Length (including style) 2.4 mm., breadth 1.8 mm. Reuver. 



We have several nuts of this species, all from Reuver. The most noticeable 

 character is the prolongation of the keel into a point which becomes part of the style. 



POTAMOGETON Sp. 8. 



PL II, fig. 8. 



Nut broadly obovate scarcely inflated, with large shallow central depression, 

 ventral margin convex and prominent above deeply concave below, dorsal margin 

 semicircular, attachment basi*lateral; style apical long straight thick directed somewhat 



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