170 PROCEEDINGS OF THE ACADEMY OF [1896. 



NOTE ON A UNIFORM PLAN OF DESCRIBING THE HUMAN SKULL. 

 By Harrison Allen, M. D. 



In a recent study of the human skull I attempted to frame a 

 method of uniform description which answers a useful purpose. As- 

 suming that the skull presents a norma frontalis, a norma basilaris, 

 a norma lateralis and a norma verticalis, the followiDg order of pro- 

 cedure is recommended. Beginning at the norma frontalis and 

 proceeding from above downward I note the following : 



The degree of prominence of the glabella and supraorbital ridges, 

 by defining an arc between nasion and ophryon, by a piece of flexible 

 wire, drawing a chord for the arc and measuring the versed sine. 

 (In a given case it would read as follows — g. and s. o. r.=5 mm.;. 

 Next the degree of deflection of the supraorbital margin is recorded 

 on a protractor. (In a given case s. o. m.^40°). 



The nasal bones yield three portions: — i\\Q frontal portion whicH 

 is bounded above by the frontal bone; the maxillary portion, which 

 lies between the frontal bone and premaxilla ; the jireviaxillary por- 

 tion which lies in contact with the premaxilla. The frontal portion 

 is measured from the union of the nasal bone and the ascending pro- 

 cess of the maxilla to the proximal free end of the lateral margin of 

 the nasal bone. The maxillary portion constitutes the greater part 

 of the bone and lies entirely in contact with the ascending process 

 of the maxilla. The premaxillary portion is the least well defined 

 and lies on the lateral margin of the bone a few millimeters above 

 the free distal margin of the bone. The suture between the pre- 

 maxilla and maxilla is never found after an early stage of develop- 

 ment ; notwithstanding this, the manner in which the premaxilla 

 and the nasal bones unite in the apes, taken together with the ranges 

 of variation in this same line, as noted in the human subject, give 

 the observer an accurate imj)ression of the extent of naso-premaxil- 

 lary junction. The texture of the naso-premaxillary suture is dis- 

 tinctive. The nasal bone is further divided into two parts, that 

 which lies in contact with the frontal bone and the ethmoid bone 

 and is outside of the nasal chamber, and that which lies below the 

 one last named and is entirely within the nasal chamber ; the first 



