X. The Bakerian Lecture.—On the organs of reproduction, and the development of the myriapoda.—First series

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Abstract
The development of the Myriapoda has hitherto been only partially investigated. It is, nevertheless, a subject of great importance to the comparative anatomist, from the remarkable fact that it takes place in a manner entirely different from that of most of the higher Articulata, to some of which the Myriapoda are closely allied both in habits and structure. The true Insecta arrive at their perfect state by an aggregation or apparent diminution in the number of their segments, but the Myriapoda, on the contrary, by a repeated increase of these parts, which in many instances are multiplied to several times their original number. This addition of segments, during the growth of the animal, occurs throughout the whole class, and is one of its chief characteristics. This fact was first noticed long ago by Degeer, but since the period of his observations nothing further was added to our knowledge until it was fully confirmed by the careful investigations of Savi, and also by the more recent labours of Brandt, Gervais, and Waga. But excellent as are the observations of these naturalists, some of the most important circumstances connected with them have been entirely overlooked, both as regards the condition of the embryo on leaving the ovum, and also as regards the manner in which the new segments are developed. M. Gervais has pointed out a circumstance in which the Scolopendradæ differ from the Iulidæ in the development of the legs, but no precise account, so far as I have been able to ascertain, has been given of the production of the segments. In the observations which I now have the honour of submitting to the Royal Society, I propose, first, to examine the organs of reproduction, and then to show the various changes as they occur in the development of lulus terrestris , one of the commonest species of the Iulidæ of this country. The reproductive parts in Iulus are exceedingly interesting on account of their simplicity of structure. Treviranus has described them in the male as two elongated tubes which terminate in separate orifices behind the seventh pair of legs, without any external organ of intromission. In the female, he says, they are composed of a long ovary, formed of two knots of eggs which extend from its outlet in the fourth segment, to its termination beneath the alimentary canal, near the anus; but in this account he has entirely overlooked the essential parts of these organs in both sexes.

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