order. The approach of Platypteryx and Cilix to the Pyralides, in assuming so much of their characters, is very interesting, and is a most striking departure from the typical form. These genera also approach the Lithosiæ, but not so nearly as some exotics. [48] British Entomology, pl. 328. [49] As the larva so decidedly forbids the introduction of this insect among the Notodontæ, and places it among the Noctuæ, it probably in some degree approaches Geometra pennaria in the adjoining sub-class. Natural Order--_Lithosiæ_. The difference between Lithosiæ and Arctiæ is rather difficult to point out; yet a difference exists, which it is perfectly impossible not to detect. The larva of Lithosiæ has sixteen feet, is very active, is moderately hairy, does not readily roll itself in ring, but occasionally assumes that attitude. The pupa is smooth, changes in a slight web, in which the hairs are intermixed. The approach of Lithosia[50] to the genus Yponomeuta, in Tinea, scarcely need be pointed out. It will be observed, that Mr. Samouelle[51] was aware of this approach, and placed the genera Lithosia and Yponomeuta following each other. The splendid Callimorpha dominula, although, to all appearance, a real Arctia, must be included in this order, and placed in contact with the following one. [50] See note for the genera of Lithosia. [51] Ent. Useful Com. p. 249. Natural Order--_Arctiæ_. Larva, with sixteen feet, generally very hairy, bear-like; rolls itself in a ring when touched; pupa smooth, in a slight web. Whether the whole of Mr. Curtis's genus Acronycta must be included in this order, I am not able positively to say: the genus Apatela of Mr. Stephens certainly must, and until I have obtained sufficient information to decide on Acronycta, we must bring Mr. Stephens's genus only into the order, leaving the remainder of the species undisposed of. The development of the antlia in Acronycta discovers as near an approach to Noctua, as Lithosia does to Tinea; but the bear-like, cocoon-spinning larva place these insects in close alliance with the true Arctiæ. Natural Order--_Lariæ_. Larva, with sixteen feet, and furnished with various brushes, or fascicles of hair, on different parts of the body, but mostly on the anterior dorsal segments; it rolls itself in a ring when touched. The genus Porthesia of Mr. Stephens may be considered a near approach to Eriogaster, in the following order, Bombyces, in many of its peculiarities, as the abdominal hair with which it covers its eggs, in its antennæ, &c. Orgyia antiqua, on the other hand, is in habit, expansion of wing, slender body, and apterous female, a close approach to the Geometræ, near the genera Hybernia and Nyssia; in fact, were it not for the larva, that is, were the larva unknown, we should have no hesitation about placing this insect with the Geometræ.