Although much has been written on the etiology of exstrophy of the bladder and its allied malformations, the problems are far from settled, and comparatively little agreement exists. Through the kindness of Dr. Philip G. Young, a rare type of this malformation, which throws some additional light on the problem of the etiology, has been studied. It is the object of this paper not only to consider the probable embryonal development of this rare type, but also to discuss the etiology of the more common types, including simple epispadiades. REPORT OF CASE History. —The mother was a primipara, and labor was normal. Neither the family history nor the physical findings during pregnancy were suggestive, and the mother has since given birth to a perfectly normal child. Dr. Young stated that the time of the birth in question he noticed particularly the shortness of the umbilical cord; but unfortunately neither the