A benign chondroblastoma of bone is reported. It was unusual because it occurred in an old lady, in a toe, and it was not painful and radiologically resembled a chondroma. The coarsely lobulated tumour showed a varied microscopic appearance, but it consisted chiefly of closely packed sheets of small, round polygonal or fusiform cells. There was some calcification present. The literature is reviewed.

1. A case of bilateral extensordigitorum brevismanuscausingsymptomsisdescribed. A review of the literature has revealed fourteen previous cases in which the anomaly was recognised.

2. The phylogenetic and morphological significance of this atavistic structure is considered.

3. Observations are made on the clinical features of the condition. It usually presents in a young male manual worker who complains of pain and swelling on the dorsum of the hand after heavy work. There is a visible swelling with the physical characteristics of a small fleshy extensor muscle.

4. Various methods of treatment are discussed. If the symptoms warrant operation total ablation of the muscle is suggested.

1. A case of discoid medial cartilage is describe—the fifth so far recorded—and comparison is made with the previous cases in the literature.

2. The origin of the anomaly, its incidence and clinical features are discussed.

3. The view is expressed that discoid cartilage is a congenital lesion due to abnormal development, fibrocartilage being laid down in mesenchyme which normally disappears in the formation of the joint. It is not the effect of arrest of a normal process or persistence of a normal foetal state. The only time at which a cartilage may be said to be disc-shaped is in the earliest weeks of embryonic life, when the disc or plaque of undifferentiated mesenchyme is present between the developing bones. The central part of this mass disappears early, and the fibrocartilage develops in its peripheral portion. In a ten-weeks'-old embryo (37 millimetres) the cartilages were shown to have a crescentic shape like that of the adult cartilage.