466 Description of two new species of Opuntia. 



X. — Description of' two new species of Opuntia ; with remarks on the 



Structure of the Fruit of Rhipsalis. By Rev. J. S. Henslow, 



M. A. Professor of Botany in the University of Cambridge. 



Sp. 1 . Opuntia Darwinii, — prostrata, articulis globoso-ovatis, aculea- 



rum validioribus elongatis tricuspdiatis, floribus magnis solitariis. 



Plate XIV. Fig 1. 

 The terminal articulation (the only one seen) globoso-ovate, with 

 distant areolae beset with short tomentum, and those towards the 

 anterior extremity with four to six stiff spines of various lengths, 

 of which the stoutest are one and a half inches long, evidently 

 formed out of three combined, and whose points are free, so that the 

 compound spine appears compressed and tricuspidate. They most- 

 ly point forward/but some spread in all directions. Flowers soli- 

 tary, larger than the articulations which they terminate, yellow. 

 Perianth of six whorls, each of five parts, gradually passing from the 

 form of small fleshy bracteal scales to membranous petaloid seg- 

 ments ; spirally arranged at somewhat more than the fifth of a cir- 

 cle asunder, so as to'form five distinct secondary spirals, correspond- 

 ing to as many, formed by the areolae on the fleshy tube investing and 

 surmounting the ovarium. These areolae are placed upon slight tuber- 

 cular elevations, each bearing a small fleshy bracteal scale, in whose 

 axil is a tuft of yellow tomentum, and those on the upper extremi- 

 ty are also furnished with about half a dozen stiff acicular spines. 

 The'segments of the perianth pass gradually from the ovate-apicu- 

 late bracteal form of those in the outermost whorl to the cuneato- 

 obcordate, and slightly mucronate petaloid form of those in the in- 

 nermost, (Fig. b.) 



Stamens numerous, covering the inner paries of the fleshy tube, 

 (Fig. c.) Style remarkably stout, cylindrical, with nine thick ra- 

 diating stigmata, reaching above the fleshy tube, and a little beyond 

 the uppermost stamens. Ovarium, a small cell, the width of the 

 style, surrounded by the very thick fleshy walls of the lower part of 

 tube or floral receptacle. The character of the herbage appears to 

 agree with that of Cactus moniliformis, Lin., which De Candolle 

 places in his division Opuntiaceae of the genus Cereus; and of which 

 division he says, " An genus proprium inter Cereos et Opuntias 

 medium ?" The flowers of our plant, however, are strictly those of 

 an Opuntia. In assigning the character of " tubum supra ovarium 

 nullum" to Opuntia, De Candolle must consider the whole of the 

 fleshy tubular portion of the receptacle to which the stamens are at- 



4 



