Many collectors have, no doubt, taken these larvae, and cast them away in the belief that they were caddis-worms. Such was the experience of the Rev. Gregory Bateman, the author of _Fresh-water Aquaria_, who says (p. 259): ‘While hunting for fresh-water animals, one not seldom comes across an insect wrapped up in two or more green leaves, or pieces of leaves, of some aquatic plant. The leaves and the animal have somewhat the appearance of a caddis-worm in its case; in fact, for a time, before I knew what it was, I mistook it (and I daresay others have done so also) for a caddis-worm.’ The cases are usually, but not invariably, made from the food-plant of the insect. Mr. Bateman has noted that these larvae ‘do not always confine themselves to the same weed, either for food or for building material.’ This has also been my experience. A larva of the Brown China Mark, recently taken on the Norfolk Broads--an excellent collecting ground for aquatic larvae--was put into a tube. The case had been damaged, and the only vegetation in the tube was a spray of bladderwort. On examining the tube, after some days, I failed to find the larva. The reason was evident on removing the cork, a small part of which had been gnawed away to procure material for the repair of the larval case, which was affixed to the under side. The larva was dead and too much decayed to be put into pickle, a circumstance I much regret, as I should like to have preserved the larva in such a strange dwelling. As it is, I have only been able to keep the house without its tenant. Pondweed is the usual home of the larva of the Brown China Mark, and from the leaves of this plant the first larval case is generally fashioned. This was the species upon which Réaumur made his interesting observations, most of which have been confirmed by succeeding observers. In well-grown larvae the contrivance by which the animal is protected from contact with the water in which it lives should be noted, as it may be easily, with the hand lens. The skin is thickly set with tiny protuberances between which the water cannot penetrate, the surface film stretching from tip to tip of these prominences, just as it does over the hairs that cover the body of a water-spider. De Geer[64] describes an aquatic larva of one of the China Marks (_Paraponyx stratiotata_), which has its breathing apparatus fashioned on a similar plan to that of Limnobia, though there is some difference in the details. He found his specimens on the leaves of the Water Soldier, and his interesting account recalls the fact to memory that this remarkable plant was at one time called the Marsh Aloe--an exceedingly appropriate name.