﻿BOTANICAL GAZETTE 



Lewis still showed only uredinia. In October Dr. Lewis and the writer again 

 visited the same area and found telia sparingly present. Only an occasional 



a leaflet. The rust is very inconspicuous, even when the host is thoroughly 

 infected with the uredinial stage, and it is almost impossible to find in the 



Ravenelia thornberiana, sp. nov. 

 O. Pycnia unknown. 



II. Uredinia amphigenous, caulicolous and fruticolous, usually 

 forming small witches' brooms 3-6 cm. long by 2-4 cm. broad, 

 consisting of a rather dense interwoven mass of abortive branches, 

 petioles, and young pods, thickly covering large areas, often con- 

 fluent on stems and pods, irregularly orbicular to elliptical or on the 

 branches oblong, very small, o. 2-0.5 mm - m diameter, subcuticular 

 early naked, cinnamon brown, ruptured cuticle noticeable; para- 

 physes abundant, intermixed with the urediniospores, clavate to 

 subcapitate, 10-13X35-57/*, heads 10-13X13-17^ average for 

 10 heads 11.6X15.8ju, apex of head fulvous, lower one-third 

 semi-hyaline, walls 2-3 p thick, rarely slightly thicker at apex, stipe 

 attenuate, hyaline, 2-4 p thick by 20-40 ju long, average for 10 

 stipes 3X31.4/*; urediniospores obovate, pyriform or oval, 16-18 

 X 20-27 /*, average for 10 spores 17X23.5 /*, walls 1.5-2/x thick, 

 sometimes slightly thicker at base, densely and evenly verrucose, 

 cinnamon brown, concolorous, pores 8-12, in two transverse zones 

 of 4-6 pores each, equidistant from the equator. 



III. Telia amphigenous and caulicolous, small, 0.2-0. 5 mm. 

 in diameter, irregularly oval, scattered, or often confluent on the 

 petioles and stems, subcuticular, chestnut brown, ruptured cuticle 

 noticeable; teliospore heads chestnut brown, 70-90 /* in diameter, 

 average for 10 heads 80 /*, 4 or 5 spores across, 8-14 marginal spores, 

 smooth; paraphyses present, stipe often not attenuate and solid, 

 otherwise as in the uredinia; cysts delicate, numerous beneath 

 entire head, in two irregular rows around stipe, subappressed, 

 easily swelling and bursting in water, becoming pendent and sub- 

 globose in water; pedicel short, hyaline, deciduous. 



On Mimosaceae. Type for uredinia collected on Acacia amstrida pauci- 



