the two supposed species. This led to a review of herl>arium 

 specimens of New Jersey material availahle under the two names, 

 also a survey of series of specimens from IMassachusetts and in- 

 termediate states to Florida. Length of leaves and leaf-sheaths, 

 nature of the prickles on the cone-scales, and geographical range 

 have been the three most important characters for separating 

 these two populations. Of these, range should be at once excluded 

 as no basis for specific segregation. The nature of the prickles 

 on the cone-scales is tremendously variable. In P. rigida the 

 prickles are usually stated to be stout, while in P. scrotina they 

 are said to be small, slender, and deciduous, or obsolete. Actually, 

 this criterion is impossible to apply. The writer has seen short- 

 leaved specimens of P. rigida from Massachusetts and New York 

 in which the prickles were very slender and mostly deciduous. 

 He has also seen long-leaved specimens of P. scrotina from coastal 

 North Carolina in which the prickles were stout. In view of such 

 a condition, this character, though perhaps indicating a tendency, 

 is exceedingly difficult to use in making determinations of indi- 

 vidual specimens. 



Length of leaves remains as the best basis for identifying trees 

 as P. rigida or P. scrotina, but this character exhibits a geographi- 

 cal gradient, as shown in the following table. 



A^o. of collections Extremes Average 



tious measured in length length 



Massachusetts^ 7 5-12 cm. 7.9 cm. 



Central Xew York 7 6-14 9.1 



Southern Xew York 6 7-12 8.9 



Xorthern Xew Jersey 4 5-11.5 9.3 



Southern Xew Jersey 13 7-23 13.5 



Maryland 3 8.5-14 11.8 



North Carolina 6 8-17.5 13.9 



South Carolina 3 10.5-18 15.4 



Georgia 2 13-21 16.8 



Florida 4 15.5-20 17.6 



^ Professor G. T. Hastings has recently sent to the writer leaf-clusters 

 from trees at Cape Ann, Massachusetts, of which the extremes in length are 

 4.7 cm. and 14.2 cm. These exceed in both directions the measurements made 

 in the above study. 



The average for southern New Jersey is perhaps higher than 

 it ought to be because more specimens from Cape May County 



