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plified by the Dragon-flies, which have them so prominent that they are sometimes supposed to be stings. By means of them the male is enabled to retain the female, and even fly about with her in such a position as to have given rise to the erroneous notion that the genitalia in these insects are placed in the anterior part of the body. In this respect they form no exception to the general rule.

Pl. V. fig. 1, represents the generative organs of the female of Athalia centifoliæ, from Mr. Newport's excellent essay on that insect: a, a, the ovarial tubes; c, c, the uterine cavities; d, the separate oviducts; e, the common or ejaculatory oviduct; f, the spermatheca; g, the poison gland, h, its vessel; 10 and 11, the terminal ganglia lying upon the ejaculatory oviduct before the sperm-bladder.

Fig. 2, generative organs of the female of Ranatra linearis, the same letters as in the preceding figure indicating corresponding parts; g, supposed swimming bladder, with a part of the intestine.

Fig. 3, male generative organs of Athalia centifoliæ, a, a, smaller testes, b, b, the ducts, c, larger testes, d, d, vasa deferentia, e, vesiculæ seminales, h, ejaculatory duct, i, exterior valves.

Fig. 4, generative apparatus of the male of Hydrous piceus; a, a, testes, b, b, vasa deferentia, c, c, principal seminal vessels, e, e, e, e, various accessory vessels, f, ejaculatory duct, dilated in the middle, g, copulative armature of the vagina.

Fig. 5, testicle of Silpha obscura greatly magnified.

Muscular System.—When we reflect on the varied movements of insects, their different modes of progression, walking, leaping, swimming, flying, &c. and the great degree of strength which they exhibit,