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DR. F. WOOD JONES ON THE 



and more especially an inspection of the actual specimens, will 

 convince anyone that the bone labelled " pi " in the two figures 

 is not the same element in the two specimens. The same criticism 

 holds good throughout the paper. From specimen to specimen 

 the irregularity of the apparent suture-lines increases, and the 

 only conclusion at which it was possible to arrive was that the 

 question was incapable of solution by an examination of adult 

 specimens ; since it was certainly essential to see the simplified 

 condition in the foetal or new-born individual. 



It was not until the present year (1917) that two foetal Lemurs, 

 preserved by Mr. R. I. Pocock, were placed unreservedly in my 

 hands, and I had the opportunity of examining the structure of 

 the orbito-temporal region before any of the post-natal, secondary 



Text-figure 2. 



The skull of a foetal specimen of Lemur catta. Actual length 39 mm. 



changes had set in. Of the two specimens that of L. catta is 

 the less highly ossified, and the constituent bones of the cranial 

 wall are seen with diagrammatic clearness (see text-fig. 2). The 

 condition of the orbito-temporal region is shown in text-figure 3. 

 The orbital plate of the frontal takes a very large share in the 

 formation of the orbital wall ; it meets the nasal and lachrymal 

 in front, but at this stage it is separated from the frontal process 

 of the maxilla by an unossified interval. Behind it meets the 

 parietal at the coronary suture, and below that it meets the 

 anterior edge of the very small orbito-sphenoid. Along the lower 

 border of the orbital plate of the frontal runs an elongated bone 

 shaped somewhat like a ploughshare. This bone articulates in 



