DICOTYLEDONEAE. 

 JUGLANDACEAE. 



PTEROCARYA LIMBURGENSIS Sp. nov. 

 PL IV, figs. 15—21. 



Endocarpium infra apiculatum, parte superiore latissimum, apicetruncatum, 

 rostro brevi triangulari distinctissimo instructum; costae irregulariter anasto* 

 mosantes. Reuver, Swalmen, Brunssum, Tegelen. 



Fruits of Pterocarya are very abundant at Reuver and Swalmen, and a few have 

 been found at Brunssum; they evidently belong to the same species as that which occurs 

 at Tegelen. The endocarps vary however so greatly in external characters that it is 

 very difficult to describe them. If extreme forms only are studied, we should be inclined 

 to refer our fossils to several species, differing in number and sharpness of the ribs and 

 in other characters; but in a very large series intermediate forms seem to connect all 

 these extremes. Some specimens approach the strongly beaked P. caucasica (figs. 26, 27) 

 whilst most are more like the smaller short*pointed P. hupehensis of China (figs. 22, 23). 



When a large series of the fossil endocarps is studied we find that certain definite 

 characters emerge by which we can with certainty distinguish these three allied species. 

 In the recent P. caucasica the endocarp is rounded below, widest in the middle, and 

 narrows gradually upward into a broad robust beak. In the Chinese P. hupehensis the 

 very broad endocarp is truncate below, widest at the lowest third, and from thence 

 narrows into a short triangular beak. In P. limburgensis the endocarp is usually pointed 

 below, widest in its upper third, truncate above with a sharply defined short triangular 

 beak. Its ribs tend also more often to form loops, and are less straight and parallel than 

 in the two living allied species. We do not however insist on this last character, for the 

 ribbing is excessively variable in the endocarps of Pterocarya, and we have not yet been 

 able to examine so large a series of the recent fruits as of the fossils. 



The Tegelen fruits previously referred to P. caucasica must now be transferred to 

 P. limburgensis; but as the figures previously given do not well show the characters of the 

 species, the type specimens of P. limburgensis must be those from Reuver shown on PL IV 

 We have re-examined all our specimens from Tegelen, and also have a large series 

 collected and sent to us by Dr. Tesch ; we cannot in any way distinguish them from the 

 Reuver forms. 



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