The mode in which the intersecting bunches of crystals are connected is shown in Fig. 2. The upper end of the cylinder is closed by a perforated cover, which probably has given rise to the name of the sponge. The upper portion of the cylinder is surrounded by a few irregular, annular masses of organic tissue, which adheres loosely only to the skeleton. The lower end is formed by a bunch of long threads, rooting firmly in the ground. [Illustration: Fig. 2.--SPONGE CRYSTALS MAGNIFIED.] Up to about ten years ago the price of specimens of this sponge was very high. At that time, however, a colony of Eucleptellas was found near the cities of Cebu and Manila, in the East Indies, in a depth not exceeding 100 fathoms, and since they have appeared in larger quantities in the market. It is remarkable that, contrary to their habits, these organisms have immigrated into regions to which they were totally unaccustomed. Yet it must be regarded as a greater curiosity that they have been accompanied to their new abode by a few animals living in equally deep water and never met with before at depths less than three or four hundred fathoms. Among these animals is a _Phormosoma_ (water hedgehog), noted for its long spines. Glass sponges are not confined to tropical regions. They are met with in latitudes as high as the Faeroee Islands, where the beautiful _Holtenia Carpentaria_ abounds. It is represented in Fig. 3. Its cup-shaped skeleton is similar in structure to that of the _Eucleptella_; numerous crystalline needles protrude from the surface of the upper part. Lately some specimens of _Holtenia_ have been found on the coast of Florida. [Illustration: Fig. 3.--HOLTENIA CARPENTERIA.] Glass sponges serve as dwellings for numerous animals, especially crustaceae. A small shrimp inhabits the tubes of the _Eucleptella_, a male and a female generally living together. They are shut up as in a prison in their crystalline home, as they are generally too large to pass through the meshes formed by the bundles of crystals. It was formerly believed that these skeletons had actually been built by the shrimps, and we can find no explanation for this curious circumstance, other than that the shrimps entered these habitations while very small and became too large to leave them. * * * * * PLANTS PROTECTED BY INSECTS.