To avoid as much as possible errors that might be attributable to a faulty mode of examination, the figures and photographs have all been made from the larvæ alive, and in their natural medium, except two instances in the drawings and one in the photographs. After alluding to the effects of various reagents which were generally found useless in “differentiating” the fine nervous structures, and the ordinary mode of branching in the nerves from the ganglionic chain, two particular methods of termination are selected as illustrative of the relation between the muscular and nervous tissues. One, termed the “flabelliform,’’ where the nerve on approaching the muscular sheath expands into a fan shape, and with its fine granular and nucleated contents embraces the muscle in form of the letter A, without any evidence of the granulai matter and sarcous elements being in absolute contact; the other, called the “stapiform” or stirrup-shaped. The latter, in its early stage, is knobbed in appearance. This, the early stage, is shown gradually passing into the cellular, looped, or stirrup form, embracing the fine muscular structure somewhat obliquely, or passing entirely round it, and projecting beyond its edge. In this form also there was no evidence of any union of the granular contents with the sarcous elements, though firm union existed between their sheaths or outer membranes. Fine networks, ending apparently in a granular irregular spot with a pale centre and uniting, are pointed out. The relation and union of short muscles passing between others, and nerve-fibres lying along side them, with flabelliform expansions, are remarked on, and shown in the figures and photographs. Muscles undergoing degeneration, or the metamorphic change, are noticed, and in no instance could a nerve-fibre be seen attached to them, or a fibre that could with certainty be traced to any nerve or ganglion. No change was observed of a definite character, as regards the mode of union, under muscular contraction. Some of the finest muscular fibres are passed by for special reasons, as constant motion &c. Attention is called to the blood-corpuscles, or to corpuscles which, for convenience, are called creeping corpuscles, and several figures given. The peculiarities of these bodies are regarded as of considerable importance, and, coupled with a remark in Dr. Beale’s contribution to the Transactions of the Royal Society, read May 21st, 1863, in reference to the movement of all forms of living matter.