the greater curvature of the stomach, but there were no secondary deposits, and its presence does not appear to have contributed to his death. A large left-sided hydronephrosis and a prostate the seat of myo-adenomatous enlargement were present. The medical officer who performed the autopsy was apparently unaware of the congenital abnormalities and unfortunately the opportunity was not taken of obtaining a bony specimen, nor of dissecting the nerves and muscles. SUMMARY A man aged 61 was admitted to hospital suffering from a cerebral thrombosis. X-ray examination revealed absence of the sacrum below its second segment, and of the coccyx. There were gross deficiency of the musculature below the knees, life-long urinary incontinence, a lax anal sphincter, and hydronephrosis.Congenital absence of the caudal end of the spine is rare, only 44 other cases having been reported during the past century.In addition to the features described in this case report-namely, extreme wasting of all muscles below the knees, urinary incontinence, and a lax anal sphincter-which are typical of the condition, it is commonly associated with flattened buttocks, dislocation of the hip, talipes, and abnormalities of the pelvic viscera. T h e muscular wasting can be correlated with interference with or absence of the appropriate spinal nerve and vertebral segment. The previous literature is reviewed and a classification is presented in the table. The aetiology is discussed in terms of failure of an organizer or suppression of an evocator. Comparisons are drawn with similar conditions occurring hereditarily, sporadically, and experimentally in animals. The suggestion is made that the spine and pelvis should be X-rayed in all cases of congenital abnormality of the genito-urinary apparatus, rectum, or anus.