Morphology of the Human Lachrymal Bone, fyc. 241 



with the lachrymal, and anteriorly with the nasal process of the 

 maxilla. In others, it has partially ankylosed above and remains free 

 below, its suture being in the plane of the sutura imperfecta of M. J. 

 Weber. This bone was first described by Rosenmuller (" Descr. 

 partium ext. ocZ/," Leipzig, 1797, p. 14), who found two instances. 

 Budge (" Henle u. Pfeufer's Zeitschrift," III, Series VII, p. 278) found 

 it 6 times in 184, and Luschka found it 7 times out of 60. Com- 

 bining these with my 10 out of 1020 sets of bones, we get an 

 average frequency of 23 in 1264, that is about 1 in 55. Taking 

 into consideration its relation to the sutura notha, it seems probable that 

 this must represent some element which tends to remain separate. 



In my instances, the detached process of bone was never wholly 

 coextensive with the part isolated in other skulls by the sutura notha, 

 but it generally corresponded to it above. In the skull of Glorvina 

 (Lady Morgan's Wild Irish Girl) the ossicle on the right is completely 

 detached, that on the left, where the bone was much larger, has 

 become ankylosed to the maxilla for a little more than the lower 

 half of its extent, and this arrangement I have also found in three 

 other instances. 



The sutura notha, or sutura imperfecta, which is related to this 

 ossicle, is remarkably constant in some form or other, usually as a 

 row of holes into which branches of the infra-orbital artery pass 

 (fig. 2). Traces of its separateness sometimes continue on the 

 inside of the maxilla even when there is little sign on the outside, 

 and not uncommonly a fissure occurs traversing the whole thickness 

 of the bone at one extremity, usually below but occasionally above. 

 It is, however, true that in the very large majority of maxillae no 

 separate continuous centre of ossification can be isolated for this 

 region, but this part of the bone ossifies continuously from the 

 anterior centre of the bone which arises below and internal to the 

 infra-orbital hole in the membrane of the face, during the latter days 

 of the fifth week of foetal life. Thus if this suture marks out an. 

 element originally separate, it must have lost its distinctness at a 

 remote period. The vessels perforating the maxilla along this line 

 pass to the ethmo-maxillary and maxillo-turbinal sutures, and end on 

 the nasal mucous surface along these lines ; indeed, in general, this 

 suture marks the distinctness of that part of the nasal process of the. 

 maxilla which overlies the anterior border of the ethmoid from that 

 part which intervenes between the ethmoid and the nasal, and the 

 ossicle last described corresponds to the upper part of the former 

 region. 



IX. The history of the development of the human lachrymal bone 

 is interesting as showing something of the limits within which 

 ossification periods vary. I have not been able to detect any trace of 

 bone until the eighth week. In one foetus of 4'25 centims., presumably 



VOL. XXXVII. E 



