I n order to explain an anomaly of the subclavian vein occurring in a man 68 years old, reconstructions of the cervical veins and lymphatics in four human embryos were made, with the following results. I n an embryo having a maximum measurement of 10 mm., the right arm is drained by a primit,ive ixlnar vein which unites with a thoraco-epigastric vein to form the dorsal subclavian vein. These vessels are shown in Fig. 1. The primitive ulnar vein is seen to receive a branch near the elbow, and distally it has many smaller tributaries which have been omitted from the drawing. There are no veins larger than capillaries along the radial border of the arm.
The thoracoepigastric vein, which is found in the lateral body wall, is represented in fishes and in all the higher classes of vertebrates. Unfortunately it has been given a great variety of names. I n the rabbit it is called the external mammary vein (Krause,l Lewis2) and this name has been applied to it in man (Poirier3). In man it has been called, in part at least, the long, lateral, o r inferior thoracic vein, but the term thoraco-cpigastyic is preferable to any of these.
The priinitire ulnar and thoraco-epigastric veins unite to form a subclavian vein which passes dorsal to the brachial plexus to enter the IKraiise, W. Die Anatomie des Kaninchens. Leipzig, 1368. 2Lewis, F. T. The development of the lymphatic system in rabbits. Amer. sPoii-ier, P. Trait6 d'anatomie huniaine.