314 PROCEEDINGS OF THE AMERICAN ACADEMY. 



4-merous, staminate and perfect: legume with glabrous valves; margin 

 armed with very short incurved prickles. — Contrib. U. S. Nat. Herb. v. 

 141. — On foot hills and in mountain woods above Cuernavaca, Pringle, 

 nos. 6200, 6385 (distrib. by clerical error as cceridescens) ; and between 

 Guichocovi and Lagunas, Oaxaca, JVelson, no. 2746. A beautiful and 

 very distinct species. 



= = Leaflets 8 to 10 mm. long. 



a. Branchlets and peduncles strigillose or covered with a sparing sub-appressed 



scabrous pubescence. 



16. M. Nelsonii. Scabrous-puberulent shrub, 3 to 6 dm. high: 

 branches woody, covered with a dull gray bark ; branchlets warty- 

 roughened : petioles short, scabrous-puberulent ; pinna? 1 pair ; leaflets 

 5 to 1 1 pairs, broadly oblong, rounded at both ends, appressed-ciliate, of 

 firm subcoriaceous texture, slightly lucid, 7 to 9 mm. long, 4 mm. broad, 

 when young finely pubescent upon both sides but sometimes early 

 glabrate, or perhaps glabrous at first, often (esjiecially the lowest one) 

 strigillose beneath : peduncles considerably exceeding the petioles, some- 

 what pubescent and strigillose: globose heads 10 mm. in diameter; 

 bracts shorter than the buds, inconspicuous ; flowers 4-merous, perfect 

 and staminate : fruit light-colored, oblong, 2 cm. in length, 6 mm. in 

 breadth, 3-4-jointed, hispid throughout with spreading curved bristles. — 

 Collected in fruit by Dr. Edward Palmer near Acapulco, between 

 October, 1894, and March, 1895, no. 88, and in flower by E. W. Nelson, 

 between San Geronimo and La Venta at 665 m. altitude, 13 July, 1895, 

 no. 2775 (in herb. U. S. Nat. Mus.). A species nearly related to 

 the Lower Californian 3£ Xanti, but differing in its more sparing and 

 scabrous pubescence, and much shorter bracts. Palmer's specimen is 

 armed with straight scattered spines, while Nelson's is unarmed, yet 

 their identity cannot be doubted. 



b. Pubescence Of branchlets and peduncles more copious, tawny-tomentose, 



spreading, softer in character. 



17. M. Xanti, Gray. Leaflets 4 to 9 pairs, oblong, pubescent 

 upon both sides, cinereous beneath, scabrous-ciliolate upon the margin, 

 about 8 mm. long: bracts exceeding the buds and conspicuous in the 

 young heads: legume 2-4-jointed, stipitate, 2 cm. long, covered with 

 fine pubescence and short scattered seta? both upon valves and margins. — 

 Proc. Am. Acad. v. 157 ; Benth. Trans. Linn. Soc. xxx. 396; Brandegee, 

 Proc. Calif. Acad. Sci. ser. 2, iii. 133. — Lower Calif, near Cape St 

 Lucas, Xantus, no. 29 ; Brandegee^ no. 183. 



