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" Nerves of the leg.— The sciatic nerve on each side as it passes from beneath the glutæus consists of three por- tions, two lateral and one median ; each of the former, one to the right and the other to the left, passes along the edges of the external vasti and within the lower ends of the bi- cipites, then over the top of the fibula, forming the peroneal nerve, and finally to the back of the foot. The two inner branches, one from each side, unite on the median line, near the trochanter, into one, which descends as far as the pop- liteal space, where it divides into two branches, which de- scend behind the tibia, one on each side of the fibula and os calcis ; the one going to the side of the foot belonging to B is the longest. The two form a right and left plantar nerve.

" The phrenic nerves on the front side were distributed separately to the diaphragm, descending on each side of the pericardium. The posterior pair united on the hinder face of the pericardium, but their distribution was not traced.

" The four vagus nerves, two from each head, were kept distinct throughout. The peculiar distribution of the recur- rent branches will be mentioned further on.

" Viscera.— A rather small thymus gland occupied the upper part of the cavity of each half of the thorax, and rose a short distance in the usual place at the base of each neck. Two complete sets of lungs existed, and between them a single pericardium enclosing two distinct hearts. These were entirely distinct from each other, but symmet- rically developed, or right and left. A single lower vena cava entered the pericardium from below, and then entered each venous auricle by separate branches ; the same was true of the upper vena cava. The venous auricles of the heart were on adjoining sides, and the arterial auricles on the sides most distant from each other. The aorta of the heart of A descended on the right side of the vertebral column of A, and that of B on the left side of its vertebral column ; in this case the right aorta, or that of A, was the one transposed, while that of B pursued the ordinary course. The innominate artery of A arose from the left side, and that of B from the right side of the arch. The recurrent branches of the vagus were in conformity with