to the cranium; and the same thing must necessarily be inferred of the external table, which is merely their substratum. These facts being established from observation, it is very easy to see how the frontal sinus, and other contemporary phenomena, take place. The evolution of the frontal sinus does not commence till the seventh year. At this time the bones of the face are still small and childish, the jaws occupied by the first set of teeth, and no acervus cerebri has yet been formed in the pineal gland. But the Wenzels inform us, from many observations, that, at this age of seven years, the brain has arrived at its full magnitude; and by inspecting their tables, copied in Milligan's Majendie, and taking the cube roots of the respective weights at seven, and the age of majority, it will be found that this averment comes very near the truth, and has only been disputed by those who did not understand how to make use of these tables. Now it is a law in the developement of the system, that when any part has arrived at its full magnitude, there occurs a sensible diminution in the circulation of that part, which I have elsewhere named stagnation, re-stagnation, and stasis, but for which it is not easy to find a proper term. When this state occurs, less blood will necessarily pass into the internal carotid, and so much more will consequently be sent to the face and outer parts of the head by the external carotid, the other branch of that trunk from which they arise at the same instant, namely, the common carotid artery. Hence the infantile and puerile brightness of eye now gradually diminishes in splendour, because it is henceforth supplied by the waning powers of the

internal carotid, while the complexion of the cheek, the volume of the face, the evolution of the teeth, the eye-brows, and the still small processes of the outer table of the skull, all sufficiently evince that the energy of the circulation has now found a new direction in the branches of the external carotid. All the parts to which this vessel carries blood, are, from henceforth, developed with nearly as much rapidity as the brain had been in the first septennial period of life. But among the bones hereby so rapidly developed, the nasal bones, the spongy portion of the ethmoidal bone, the external table of the os frontis and the ossa malæ, have their full share. But as the growth of all these bones, except the os frontis, is forwards, and as this bone always maintains an exact harmonic continuity with the other bones of the transverse suture, it is necessarily brought forward along with these bones. It cannot carry the diploë along with it, which substance not being so well nourished, will tend to become ab sorbed. The same effect will be greatly promoted from another cause. The schneiderian membrane growing at the same time with great rapidity, advances through the infundibular passages of the ethmoid bone, is now in immediate contact with the decaying fibres of the diploë connecting the two tables of the frontal bone, which may not yet be absorbed, and passing through amongst these, whilst the pulsation of its vessels causes them to be removed, it gradually scoops out for itself a wedge-shaped cavity between the two tables, which we denominate the frontal sinus. This sinus is not completed till twenty-one, or about the time when the bones of

the face are fully perfected; but that this is the mode in which it proceeds, may be determined by inspection of the sinus in skulls, at the different ages from its commencement in the seventh year, to the period of its final developement. Having given many facts in confirmation of this theory of the origin of the frontal sinus, in my notes to Majendie's Physiology, editions third and fourth, I shall not enlarge more on the matter here, but conclude by observing that this view of the frontal sinuses does not seem liable to any serious objection. The eminences, therefore, and developement of parts, situated over the frontal sinuses, can have no relation to, or congruence with, the parts of the brain within.

ON

IMPERFORATE HYMEN.

BY JAMES MILMAN COLEY, ESQ.

BRIDGNORTH:

Member of the Royal College of Surgeons, in London; Member of the Medical and Philosophical Society at St. Bartholomew's, &c.

THE obstruction in the vagina, occasioned by a preternatural formation of the hymen, may be either complete or incomplete. In the former case the imperfection may remain undiscovered, until the menstrual secretion has accumulated within the cavities of the uterus and vagina, and has distended the former, so as to excite suspicion of the existence of pregnancy. As the aggregation of the menses, and consequent enlargement of the uterus advance, some difficulty in discharging the urine takes place, constituting dysury; but I am not aware that any instance has been hitherto recorded, in which retention of urine, from the above cause, requiring the continued use of the catheter, has occurred. Such a disease is no where described,* either in the nosological systems of Linnæus, Vogel, Sagar, Cullen, .

* A case, with suppression of urine, related by Benevoli, is referred to in Burn's Principles of Midwifery, Ed. 6, p. 64; and others are noticed by Dr. Davis.-C.

Good, or the voluminous species and varieties of Sauvages; and no notice is taken of it by Hawley, in his classical "Definitiones Morborum.” Should a second edition of Good's physiological system of nosology be required, the editor may adopt this as a fifth variety of paruria, under the denomination of paruria retentionis hymenalis; or it may, with propriety, be incorporated in the common systems, under the title of ischuria hymenalis.

In the following case, the ischury attracted the first and undivided attention of the patient and medical attendant: the preceding symptoms of vaginal obstruction, having escaped observation.

March 25, 1832, I was requested to visit a young lady, aged 16, who resided at a considerable distance. from this town. She had been ill three days and nights, with retention of urine; and her medical attendant had been under the necessity of relieving her by the introduction of the catheter, twice daily, during that period. The existence of so distressing a disease excited great apprehension; and my opinion was solicited respecting its nature and treatment. I found the cause of the ischury to consist of an imperforate hymen, which, by totally preventing the discharge of the menstrual fluid, had produced a mechanical obstruction in the urethra. The external orifice of the meatus urinarius was situated in a cul-de-sac, and the hymen was tense and slightly protruded. The bladder having been evacuated, I proceeded to examine the hypogastrium, where I discovered an obvious and considerable enlargement of the uterus of an oblong shape, extending nearly to the umbilicus. The lower part of the abdomen had been increasing in