7 V CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



rather superficial examination, and, one would Bay, "i n<> comparison whatever. 

 The total absence of those trans> erse rugosities and also of the small resiniferons dots 

 that mark the bod) of the more genuine species of the genus, are to my mind more 

 significant differences. Another distinction, and one which I note as more important 

 than the absence of a \\ inn is, that, \\ hile the Beed-bearing pari of tin- typical Ptelea 

 samara i- thin, so thin a> t" rise but a Utile above t hi- wing on **i 1 1 nr hoe, the nut «>f 

 P.apUrais thick and strongl) double-convex. Lastly, this nut is dehiscent 



upon edge and struck with a tack hammer, it -['lit- into two valves Bfl readily a- an 



almond, whereas the Beed-bearing l><>dy «>t the Bamara "t" ordinary Ptelea can be turn 

 open but with difficulty, and at any other pari with lesB difficulty than along the 

 - where the sutures ought to be. 



