Utricularia nelumbifolia, amethystina, griffithii, caerulea,
orbiculata, multicaulis.

As I wished to ascertain whether the bladders on the rhizomes of other species of Utricularia, and of the [page 442] species of certain closely allied genera, had the same essential structure as those of Utricularia montana, and whether they captured prey, I asked Prof.  Oliver to send me fragments from the herbarium at Kew.  He kindly selected some of the most distinct forms, having entire leaves, and believed to inhabit marshy ground or water.  My son Francis Darwin, examined them, and has given me the following observations; but it should be borne in mind that it is extremely difficult to make out the structure of such minute and delicate objects after they have been dried and pressed.*

Utricularia nelumbifolia (Organ Mountains, Brazil).—­The habitat of this species is remarkable.  According to its discoverer, Mr. Gardner, it is aquatic, but “is only to be found growing in the water which collects in the bottom of the leaves of a large Tillandsia, that inhabits abundantly an arid rocky part of the mountain, at an elevation of about 5000 feet above the level of the sea.  Besides the ordinary method by seed, it propagates itself by runners, which it throws out from the base of the flower-stem; this runner is always found directing itself towards the nearest Tillandsia, when it inserts its point into the water and gives origin to a new plant, which in its turn sends out another shoot.  In this manner I have seen not less than six plants united.”  The bladders resemble those of Utricularia montana in all essential respects, even to the presence of a few minute two-armed glands on the valve.  Within one bladder there was the remnant of the abdomen of some larva or crustacean of large size,

* Prof.  Oliver has given (’Proc.  Linn.  Soc.’ vol. iv. p. 169) figures of the bladders of two South American species, namely Utricularia Jamesoniana and peltata; but he does not appear to have paid particular attention to these organs.

  ‘Travels in the Interior of Brazil, 1836-41,’ p. 527. [page 443]

having a brush of long sharp bristles at the apex.  Other bladders included fragments of articulate animals, and many of them contained broken pieces of a curious organism, the nature of which was not recognised by anyone to whom it was shown.

Utricularia amethystina (Guiana).—­This species has small entire leaves, and is apparently a marsh plant; but it must grow in places where crustaceans exist, for there were two small species within one of the bladders.  The bladders are nearly of the same shape as those of Utricularia montana, and are covered outside with the usual papillae; but they differ remarkably in the antennae being reduced to two short points, united by a membrane hollowed out in the middle.  This membrane is covered with innumerable oblong glands supported on long footstalks;