OCR Text |
Show 1 34 DR. C. I. FORSYTH MAJOR ON THE [Feb. 19, Before proceeding to a review, one by one, of the genera of Primates, a few general remarks on the lacrymal region will be necessary. The crista lacrymalis posterior of H u m a n anatomy is the vertical crest dividing the lacrymal into an anterior portion, the sulcus lacrymalis, and a posterior. The crista lacrymalis anterior is that part of the frontal process of the maxillary which in M a n forms medially the lower orbital margin, in front of the sidcus lacrymalis. W e can best describe the two fundamental types which interest us here, by stating that in Lemurs, as a rule, the crista lacrymalis posterior rides on the lower orbital margin, of which therefore it forms a portion (PI. XI. fig. 4, text-figs. 27, 28, 31, 37) ; the anterior part of the lacrymal thus becoming the pars facialis, the posterior part the pars orbitalis. In M a n and Simiidse it is the crista lacrymalis anterior which rides on the lower orbital margin, descending posteriorly into the orbit, where it forms the anterior part of the sulcus 1., and, jointly with the hamulus lacrymalis, delimits the lacrymal fossa. As a result, we have the lacrymal fossa outside the orbit in the first type, inside the orbit in the second (PI. X I . figs. 7 & 8). PROSIMI^E. Adapis parisiensis. i\ The only Tertiary Lemur of which the lacrymal fossa is known to m e is Adapis parisiensis. T w o skulls from the French Phosphorites, in the Geological Department, show this region well Text-fig. 30. Orbital region of Adapis parisiensis (Br. M . Geol. Dep. No. M 1345), about 5 nat. size. (Lettering as in text-fig. 26.) preserved, especially the younger one (text-fig. 30), which exhibits beautifully all the sutures. |