

Morphology of the Human Lachrymal Bone, fyc. 239 



4. Ossiculum hamuli. 



5. Ossiculutn infra-orbitale. 



6. Ossiculum maxillo-frontale. 



Ossiculum ethmo-lachrymale superius (figs. 11, 23). In seven speci- 

 mens I found this small ossicle behind the normal lachrymal in the 

 upper part of the ethmo-lachrymal suture ; in one of these, in a 

 Kaffir, the ossicle occupied the entire space of the small ethmo- 

 lachrymal suture, above a long ascending ethmo-lachrymal spine of 

 the maxilla (fig. 23). In another specimen (fig. 11) the bone was large, 

 and also completely separated the ethmoid from the lachrymal. This 

 form is described by Krause (p. 69) as the os lachrymals posterius, 

 and in most cases it is, as he has described, a dismemberment of the 

 os planum. In one, however, I found this bone to overlie the ethmoid. 

 A similar ossicle is described by Henle (p. 129). In the large sized 

 forms it is really ethmoidal ; in none did it extend back as far as the 

 anterior ethmoidal foramen. In these forms it is a persistence of a 

 commonly present separate centre of ossification in the front of the os 

 planum (fig. 7). 



Ossiculum ethmo-lachrymale inferius (figs. 11, 18) is a similar bone, 

 not usually of ethmoidal origin, at the lowest part of the ethmo- 

 lachrymal suture, between these bones and the maxilla. In one case 

 only it was truly ethmoidal ; in others it was supra-ethmoidal, and 

 seemed to be a separated ossicle of the infra-orbital plate of the 

 maxilla, which often (fig. 27) is irregularly cleft in this region. In 

 fig. 11, it will be seen coexisting with a divided maxilla; and in 

 fig. 23 a long cleft underlies the superior lachrymo-ethmoidal ossicle. 



Ossiculum canalis naso-lachrymalis was so named by Gruber, and 

 is a small bone lying external to the bony or membranous hamulus, 

 and in front of the sutura infra-orbitalis transversa when such exists, 

 usually coexistent with a sutura verticalis, at the commencement of 

 which it is placed. This bone was first described by Beclard 

 (" Memoires sur FOsteose, Nouvelles Journal de Medecin," IV, 

 1819, p. 332), and afterwards by Rousseau (" Annales des Sciences 

 Naturelles," XVII, 1829, p. 86, PI. V). Other anatomists have 

 referred to it, but the extensive monograph on the subject by Pro- 

 fessor Gruber (" Mem. de 1'Acad. Imp. de St. Petersbourg," VII 

 Series, vol. 24, No. 3) is so full that to it little can be added. Pro- 

 fessor Gruber regards the bone described by Beclard as distinct from 

 the ossicle of Rousseau ; but, while this maybe, the descriptions given 

 by these authors are not sufficiently definite to enable us to decide. 

 In general, this bone is quite distinct from the hamulus, and coexists 

 with it in the majority of cases, and corresponds to a variable amount 

 to the outer inferior edge of the lachrymal in one of my cases, com- 

 pletely excluding it from contact with the maxilla. 



The frequency of occurrence of this bone has been differently 



