1898.] NATURAL SCIENCES OF PHILADELPHIA. 393 



months. Conduction of water in this stem was accomplished with- 

 out the aid of root pressure, without any appreciable influence on 

 the part of the small green leaves in drawing up the liquid by the 

 pumping action of transpiration. 8 

 Pedregal near Tlalpam, Aug. 22. 



F. Pedregal near Tizapan, Valley of Mexico. 



Tizapan is a suburban village of the City of Mexico, much higher 



in elevation above the floor of the valley than Tlalpam, which lies 



to the northwest of Tlalpam. The pedregal near Tizapan presents 



the same rugged characters as elsewhere. Along its edge, here, 



runs the small stream known as Rio Cherubusco. The region 



shows the same profusion of flowering plants as elsewhere in the 



pedregal. 



TILICES. 



102. Pellaea gracilis. 



Pedregal, 7,500-8000 feet, Aug. 25 (334). 



COMMELINACE^l. 



103. Tradescantia crassifolia Cav. Ic, I, 54, t. 75 ; Bot. Mag., t. 1,598 ; Biol. 



Centr. Amer. Bot., Ill, 391. 



North and South Mexico, pedregal (Bourgeau). Pedregal, 7,500 

 -8000 feet, Aug. 25 (227). 



DIOSCOREACEjE. 



104. Diosoorea sp. 



Pedregal, 7,500-7,800 feet, Aug. 25 (440). 



PORTULACACE^l. 



105. Calandrinia grandifiora Lindl. Bot. Beg., t. 1,194. 

 Pedregal, 7,500-7,800 feet, Aug. 25 (337). 



LEGUMINOSJE. 



106. Eysenhardtia amorphoides H. B. & K. Nov. Gen. et. Sp., VI, 489. 

 Pedregal, 7,500-7,800 feet, Aug. 25. 



107. Zornia diphylla Pers. Syn., II, 318. 

 Pedregal, 7,500-7,800 feet, Aug. 25. 



108. Cassia sp. 



Pedregal, 7,500-7,800 feet, Aug. 25. 



8 See abstract of paper Water Storage and Conduction in Senecio praecox 

 from Mexico, read at Soc. Botanical Physiologists and Morphologists at Cor- 

 nell University, in Bot. Gaz., Feb., 1898, p. 116, also Science, n. s., vii, p. 120. 



26 



