240 Prof. A. Macalister. Notes on the Varieties and 



stated. Rousseau says five or six out of every ten ; Gruber says in 

 the majority of cases ; Krause, on the other hand, says in 20 per cent. 

 In my series, I find that it is present as a distinct element in 32 per 

 cent., but that there are traces of its having been present in many 

 others in which it has lost its separateness by ankylosis, so that, on 

 the whole, there are traces of its existence in 55 per cent, of crania. 

 In shape it is crescentic, trigonal, quadrate, or irregular ; in length it 

 varies from 0'5 millim. to 7 millims. When the hamulus exists, the 

 ossicle is excluded from the lachrymal canal by it, and I have never 

 found it stretching beneath the hamulus so as to come into the wall of 

 the tube. In cases of unossified hamulus, it usually forms part of the 

 bony margin of the canal, dipping into it for not more than 1'5 

 millims., and underlying the lachrymal branch of the infra-orbital 

 artery. This ossicle always lies on the maxilla and indents it, and 

 not the lachrymal ; and when it ankyloses, it is usually with the 

 maxilla, not with the lachrymal, unless in exceptional cases. In 

 nature it seems to be, like the inferior ethmo-lachrymal ossicle, a 

 detached ossicle of the maxilla, one of several ossific nuclei of the 

 orbital plate which has not coalesced with its neighbours. 



The ossiculum hamuli is a separate ossification in the membranous 

 hamulus (figs. 9, 13, 14, 15, 17, 21, 26) at the anterior attachment of 

 the membrane, that is, at the front border of the lachrymal groove, 

 separated by a vacant space or suture from the crista lachrymalis. 

 In this form I have found it in 1 per cent. Sometimes it is large, 

 extends backwards and replaces the hamulus, and it may coexist with 

 the last ossicle and exclude it from the margin. In some cases, one 

 ossicle of large size seems to replace the two (fig. 14). This bone is 

 always at the margin of the canal, and never coexists with a developed 

 hamulus ; in six specimens it encroached on the face, and formed the 

 pars facialis (fig. 13). 



The ossiculum infraorbitale marginale (Gruber) is a small nodule in 

 front of the malar, and belonging to it rather than to the lachrymal. 

 I have found it to articulate with the lachrymal hamulus, with the 

 ossiculum canalis, or with the ossiculum hamuli, but I reserve the 

 descriptions of these as they really belong to the malar bone. When 

 ossified to the malar, and extended to the lachrymal, they produce 

 the condition of lachrymo-jugal suture (Gruber, loc. cit., "Proc. Royal 

 Irish Academy," Nov. 1874, p. 58). 



Ossiculum mazillo-frontale is a bone present in 1 per cent, of my 

 specimens, and formed by a detached slip of the maxilla along the 

 upper part of the crista lachrymalis anterior. This is the nebenthrdnen- 

 bein of Luschka (" Miiller's Archiv," 1858, p. 304) which Krause finds 

 to exist in 3 per cent., a degree of frequency not present in my 

 specimens. It is variable in size, usually an elongated triangle with 

 its apex downwards articulating above with the frontal, posteriorly 



