ROBINSON. — SPECIES OF MIMOSA. 307 



to repeat here the well-known generic characters. A word may be said 

 regarding the derivation of the name. At least it may be stated that no 

 satisfactory etymology has thus far been suggested. The traditional 

 derivation from mimus, a mimic actor, which has for many years been 

 handed down in our text-books, was early given by Tournefort. Tlie 

 name, however, dates back of Tournefort, and his explanation is in 

 several regards unsatisfactory. In the first place no ordinary rules of 

 word-composition would lead to the formation of a Latin substantive 

 endins: in osa from another ending in us. Nor if such derivation could 

 be accomplished does it explain the traditionally long o of the penulti- 

 mate syllable. Prof. J. B. Greenough has suggested a possible connec- 

 tion with a theoretical (although never actually used) active participle 

 /At/xoSo-a from fjLLixiojxaL. Further light upon this subject is desired, but 

 the writer has not had an opportunity to follow the matter historically 

 beyond a few of the more accessible works. Any derivation from /ai/aco, 

 an ape, seems also to offer philological difficulties. 



No authentic specimen of the doubtful M. arcuata, Mart. & Gal., 

 has been seen, but from the original description, Bull. Acad. Brux. x. 

 pt. 2, 308, it would seem near to, if not synonymous with, M. biuncifera, 

 Benth. 



M. GEMiNATA, DC. (Prodr. ii. 427 ; A. DC. Caiques des Dess. t. 

 205), is wholly dubious. 



Subg. 1. AsTATANDRA, n. subg. Flowers polygamous in the same 

 head ; staminate flowers with twice as many stamens as segments of 

 the corolla ; perfect flowers with stamens of the same number as the 

 segments of the corolla. 



1. M. tequilana, Wats. Low branching tawny-hirsute annual, 

 armed with weak scattered spines : pinnte 1 pair ; leaflets one or two 

 pairs upon each secondary rhachis,* obovate, i-ounded and mucronate at 

 the apex, thin, sensitive, glabrous above, appressed-villous with tawny 

 hairs beneath : flowers in small ovoid heads : corolla 3-4-toothed : calyx 

 obsolete : legume armed on edges and valves with weak straight spread- 

 ing spinescent bristles. — Proc. Am. Acad. xxii. 409 (1887). — Hill- 

 sides, Tequila, Jalisco, Palmer, no. 378, August to September, 1886, 

 and in the same locality, Pringle, no. 4596. Placed in the ModestcB hj 

 Dr. Watson, who seems not to have noted the two kinds of flowers with 

 differing andrreciums. 



* When the number of leaflets is given in this paper, it applies merely to those 

 upon a single secondary rhachis, not to those of a whole leaf. 



