Dr. G'. C. Wallich on Structural Variation iri Rhizo^ods. 215 



other parts of fructification (no leaf examined) ; hairs of scape 

 jointless, and not glandular, Dendrobium nobile: raphides 

 abundant in very young leaves, less so in old leaves and stem, 

 and very rare in the root. D. pulchellum : bundles of raphides in 

 the stem and fleshy leaves, and very rare in the root. Leaf 

 of another Dendrobium : raphides rather scanty, but large. 

 Leaf of Aerides odorata : several bundles of raphides, but not 

 abounding. Bit of leaf of Trichotosia (a section oiEria) : bundles 

 of large raphides abundant in cells, and numberless smaller 

 raphides in the field of vision ; hairs of leaf red, smooth, jointless, 

 swollen at base, and not glandular. Schomburgkia crispa : bundles 

 of raphides abundant in swollen part of stem, scarcer in its thin 

 part and leaf; woody part of stem made up of dotted vessels. 

 Cattleya MossiiB (leaf and swollen part of stem) : raphides abun. 

 dant. Phaius grandifolius : bundles of raphides swarming in 

 the leaves, bulb, and root-fibres ; in the bulb, raphis-cells very 

 large and hyaline, also a profusion of beautiful, conical, large 

 starch-granules, average length -^h;^^, and breadth —J-oth of 

 an inch. Brassia (a bit of the leaf, as also in all the follow- 

 ing) : raphides, but not very plentiful. Oncidium : very few 

 bundles of raphides. Megaclinium : raphides abundant, and a 

 beautiful subcuticular sphseraphid tissue (Annals, Sept. 1863, 

 PI. IV. fig. 13) ; the diameter of each of the sphseraphides 

 regularly about -g-rroth of an inch. Ansellia : raphides rather 

 numerous. Bolbophyllum : raphides pretty numerous. 



Aracece. — Among some fragments of plants to aid this inquiry, 

 ■which were obligingly supplied by Mr. Cox, the excellent super- 

 intendent of the Redleaf Gardens, is part of the leaf of Richardia 

 cethiopica, which I find abounding in biforines, the raphides 

 escaping, under gentle pressure, regularly from both ends of the 

 oval cells. 



Edenbridge, Feb. 12, 1864. 



Erratum. — In the February Number, page 121, line 34, for "classifi- 

 cation " read " discrimination." 



[To be continued.] 



XXVL — On the Extent, and some of the Principal Causes, of 

 Structural Variation among the Difflugian Rhizopods. By 

 G. C. Wallich, M.D., F.L.S., &c. 



[Plates XV. & XVI.] 



The wide range of variation manifest in the external characters 

 of the non-testaceous Amoeban and Actinophryan Rhizopods 

 has been already discussed by pie in several papers which have 



