The Saturnians are a group of large, naked caterpillars, which are generally short, thick, clumsy, and cylindrical; they are leaf eaters, and some of them, when young, keep together in families, but separate as they become older, when they spin large silky cocoons sometimes among leaves, which they secure by silk to the twigs, sometimes attaching them to the stems and limbs, and at others at, or beneath, the surface of the ground. This group contains some of the largest and most beautiful moths, with large woolly bodies, and widely extended, highly colored and ornamented wings. They lay a great many eggs; some females deposit several hundreds. Still they are seldom so numerous as to commit serious devastations. "Among these are the _Telea Polyphemus_, _Tropæ aluna_, _Callosamia Promethea_, _Platysamia cecropia_, (formerly known under the genus _Attacus_, which is now restricted to the immense _A. Atlas_, and another species of China), and the _Euchronia Maia_, and _Hyperchiria varia_, (formerly known under the genus _Saturnia_, which is now retained for several European species). The latter species, (_H. varia_), has been generally known among us under the name of _Saturnia Io_, but according to Dr. Packard, (who published 'a Synopsis of the Bombycidæ of the United States,' in the Third Volume of the Proceedings of the Entomological Society of Philadelphia), our species has been confounded by authors with Cramer's species '_Io_,' from South America, and which belongs to a different genus."--[E.T. Cresson, Mss.] These moths may yet become valuable for the production of a kind of silk, as they are enclosed in large cocoons, the fibres of which surpass those of the Silk-worm in strength, and might be employed in the formation of fabrics, similar to those manufactured in India from the Tusseh and Arrindy Silk-worms, the strength and durability of which are proverbial. Mr. Pullein, who experimented with the cocoons of the _Cecropia_ found that twenty threads of this silk, twisted together, would sustain nearly an ounce more in weight than the same number of common silk.--(Vide Harris, pp. 295-303.) _Psychidæ_ are curious caterpillars, which, being naked, cover themselves during the larva state with a case that protects their bodies, though open at both ends, and which they carry about with them; these cases are made up of fragments of leaves, generally the stems and veins, which they connect together by threads of silk. The Germans call them Sack-bearers. Huebner called them _Canæphoræ_, or Basket-carriers, because the cases, often made of little sticks, resemble a basket. One genus is called _Oeceticus_, or House-insect; and the common species, which, in some parts of the country, commits great devastation upon the leaves of trees, is called the Drop-worm, or the Basket-worm, in many places.