35 



ANATOMY OF THE GYMNOSPERMS 



uniform but conspicuously unequal, disposed in unequal and some- 

 what irregular rows ; those of the spring wood thin-walled, about 

 32 x 39 /A, those of the summer wood rather thin-walled, about 1 9 x 29 p.. 

 Medullary rays very resinous, broad, i cell wide, and distant about 2-8 

 rows of tracheids. Specialized resin cells wholly wanting. Resin 

 passages numerous, large, chiefly in the spring wood and filled with 

 prominent, resinous thyloses, the epithelium 1-2 cells thick, and not 

 extended into parenchymatous tracts. 



Radial. Bordered pits very numerous in i row, rarely contiguous ; round, 

 more rarely oval, and about 17.5 /A, the round orifice about 7 /x; in 

 the summer wood somewhat reduced. Pits on the tangential walls of 

 the summer wood prominent, large, somewhat numerous. Medullary 

 rays very resinous ; ray tracheids wholly wanting ; parenchyma cells 

 all of one kind, more or less contracted at the ends, very variable 

 but generally equal to about 3-5 spring tracheids ; the upper and 

 lower walls strongly and rather frequently pitted ; the terminal walls 

 coarsely pitted or locally thickened ; the lateral walls with rather small, 

 oval pits, chiefly i per tracheid throughout, or in the marginal cells 

 and low rays 2 per tracheid. 



Tangential. Fusiform rays numerous, medium ; the cells thick-walled ; the 

 central tract broad and occupied by i large resin canal filled with 

 thyloses; the terminals chiefly short or rarely prolonged with 1-2 

 seriate cells. Ordinary rays very variable but chiefly low to medium, 

 sometimes more or less 2-seriate in part ; very numerous ; the cells 

 broad but variable and round, oval or squarish, chiefly equal ; in the 

 low rays commonly becoming oblong. 



The middle Cretaceous at Kreischerville, Staten Island. Material in the 

 form of lignite (Jeffrey). 



49. * * P. scituatense, Jeff, and Chrys. 



Transverse. Growth rings rather broad but thin, the limits obscured by 

 displacement of structure ; summer wood chiefly broad, the transition 

 from the spring wood apparently gradual. Tracheids all rather thin- 

 walled, those of the spring wood about 26.7 x 44.5 it. Medullary rays 

 numerous, prominent, resinous, broad, i cell wide and distant about 

 2-5 rows of tracheids. Resin canals rather numerous, chiefly in the 

 summer wood and central to broad tracts of parenchyma ; devoid of 

 thyloses, rather small, regularly oval or round, the epithelium composed 

 of a single layer of rather small, rounded, and somewhat thick-walled 

 cells. Wood parenchyma resinous, the cells large, thin-walled ; forming 

 extensive and prominent tracts about the resin canals often 427 x 570 /x 

 broad. 



Radial. Bordered pits in i row, somewhat distant and not numerous ; 

 round, about 24.6 p. broad, the lenticular orifice showing a cross ; not 

 much reduced in the summer wood. Pits on the tangential walls of 

 the summer tracheids not determinate, apparently wanting. Medul- 

 lary rays resinous ; ray tracheids apparently wanting ; the parenchyma 

 cells all of one kind, not contracted at the ends, equal to about 5-8 

 wood tracheids ; the upper and lower walls rather thick, distantly and 



