( 861 ) 



Fruotus dimidio brcvior eo /). .v/>^///inrm tarnen latior, long. (rostro 

 incluso) ('irciter 3—5 mm.; setae 7 vel 8 (foi-si(an 9), longitudinal iter 

 complanatae, canaliciilatae, striatae; mix ovata snbito in stipiteni 

 coarctata, in lostrum longum graeile atteniiata, paulo triangularis 

 vel plano-convexa, praesertini rostrum versus; superticies foveolata, 

 multangula, ea D. spathaa'i. cvus^iov, long. (rostro excluso) 2.0— 2.5 

 mm., lat. 1 mm. 



Figs. 1—8, photographed on the same scale, show the diflferenees 

 between the recent and fossil forms. In the living species the nut is 

 oblong, not ovate, and is much narrower iji |)roportion to its lenoth. 

 The long stalked nut with oblique aKachment, inarticulate style, setae 

 more than 6 with recurved hooks, are generic characters commoji 

 to the two species. In section the nut of D. ms7>^ƒ6»ry>/^Ms somewhat 

 triangular near the base, becomes plano-convex in the middle, but 

 loses its convexity as it passes into the beak; the beak at its base 

 is tlattened triangular, but becomes terete above. 



As all the specimens we have yet seen (about 20) have apparently 

 germinated, it is impossible to describe the exact shape of the nuts 

 or the complete setae ; we have therefore figured several actual 

 specimens, without attemptijig to restore them. The setae are more 

 or less broken, but we cannot find clear evidence of. more than 8 

 ill any of the specimens ; they differ from those of D. spatJt,aceum 

 in their tlattening, and they are longitudinally channelled instead of 

 showing a midrib. The fruits undoubtedly belong to the genus Duli- 

 chiuin ; and as the living species has a wide range in latitude we 

 thought it possible that some form (several different ones have been 

 recorded) might agree with our fossil. We find, however, that the 

 fruits of the recent forms in the Kew herbarium vary only slightly ; 

 they are always much larger than our fossil, and the nut is long, 

 narrow, and parallel-sided. 



Whether the genus Dullvldmn originated in Europe or in North 

 America there is nothing to show. It has now only one living spe- 

 (ües, confined to America ; but this species has been found also in 

 a fossil state in Denmark. Now, in an older deposit in the province 

 of Limburg, we discover an extinct form. Very little is yet known 

 as to the geological history of the Cyperaceae, and DuUckium will 

 probably turn out to have been widely distributed and to have had 

 many species. The genus is at present very isolated and (he new 

 fossil form makes no approach to any other genus. 



00 

 Proceedings Royal Acad. Amsterdam Vol. X. 



