ORBJTO-TKMPOHAL REGTON OF SKULL OF LEMUR 



325 



this region in the Lemurs. The first two (those of Duckworth 

 and Forsyth Major) admit the presence of the os planum of the 

 ethmoid, but differ widely as to the arrangement of the different 

 elements. The second two (those of Grandidier &. Milne Edwards 

 and Flower, and of Cuvier) exclude the presence of an os planum 

 of the ethmoid, but differ as to the elements which overlie and 

 exclude this bone. The position will be simplified by reducing 

 the four diagnoses to diagrams in which cognisance is taken only 

 of the elements which are in dispute (see text-fig. 1). 



Text-figure 1. 



Diagrams to represent the diagnosis of the elements entering into the formation 



of the orbital wall of Lemur . 



i7\= frontal. L.= lachrymal. E.= ethmoid. ' PaZ.=palatal. Jf.=maxilla. 



A. According to Duckworth. B. According to Forsyth Major. . 



C. Accordiug to MM. Grandidier & Milne Edwards, and also Flower. 



D. According to Cuvier. 



It is often impossible to comment upon the work of previous 

 authors unless their written statements can be correlated with 

 the specimens from which the descriptions were taken. Indi- 

 vidual variation may play a large part in discordant description, 

 and for this reason it behoves every author to specify the material 

 from which his descriptions are drawn. In only one case (that 

 of Dr, Forsyth Major) is this condition fulfilled. In every case 

 in which he describes and figures a specimen he notes its number 

 in the National Collection preserved in the British Museum. 



It was therefore the diagnosis of Forsyth Major that I first 

 attempted to verify. In 3 914, by the kind permission of 

 Mr. Oldfield Thomas, I examined the actual specimens described 

 in the paper of 1901. The conclusion I arrived at was that the 

 problem was one of exceeding difficulty when confined, as it was 

 in this case, to the skulls of adult Lemurs. But I also gathered 

 the impression that the interpretation of presumed suture-lines 

 described and figured by the various authors was, in many cases, 

 open to grave doubts, and that the so-called " os planum" was not 

 in all cases the same element (see figs. 65 & 66, p. 258, op. cit., of 

 , specimens 97.9.1.18 and 97.4.6.1). A glance at these two figures, 



