8 NIL9 GYLDENSTOLPE, THE SWEDISH ZOOLOGICAL EXPEDITIONS TO SIAM. 



In his »Review of the Prirnates » Elliot lias given a »key to the species » (Vol. I 

 p. 23). He there de vides these animals into two distinct groups which are being charac- 

 terized as follows: 



»Group A: Skulls with sagittal crest; incisors two.» Against this stånds: »Group 

 B: Skulls without sagittal erests; incisors four. » 



To the first group Elliot refers Nycticebus borneanus and Nycticebus bancanus. 

 Both these species are described by Lyon (Proc. U. S. Nat. Mus., Vol. 31 p. 527 — 538) in his 

 »Notes on Slow Lemurs». Even Lyon unites these two species into one group, but in 

 his key (p. 531, tom. cit.) he writes: »Temporal ridges not meeting or approximating 

 each other in old age, but forming two parallel ridges on top of skull; no specimens, not 

 even newborn young show more than one incisor on each side of the upper jaw». 



Lyon, when describing N. borneanus says (p. 536): »Temporal ridges ne ver uniting 

 to form a sagittal crest, forming instead two parallel ridges on top of skull». 



As concerning N. bancanus Lyon says: »Skull similar to that of Nycticebus bor- 

 neanus». As seen by this Elliot's »statement» is absolutely opposite to the fact. The 

 same is also the case with his Group B, which is characterized by Elliot with the follow- 

 ing words: »Skulls without sagittal erests; incisors four». 



About this group Lyon says: »Temporal ridges meeting or approximating each 

 other in old age, eventually forming a sagittal crest on top of skull. » 



This latter statement is also confirmed by the material at my disposal. The male 

 specimen has a well developed sagittal crest measuring about 15 mm. in length. In the 

 female specimen, however, there is no crest, but the temporal ridges are only separated 

 from each other by a narrow space and would probably ha ve formed a crest if the speci- 

 men had grown older. 



Elliot's statement about the teeth is also misleading, because in the second 

 group the species in many cases are only provided with two upper incisors when adult. 

 This is always the case with Nycticebus hilleri Stone & Rehn and in accordance with 

 Lyon's description. In N. malaianus Anders, and N. javanicus E. Geoffr. the upper 

 incisors may be two, three and four in adult specimens. 



Milne Edwards described in Nouv. Arch. du Mus. Bull. III. 1867. p. 11 a specimen 

 of Nycticebus received from the vicinity of Bangkok and ga ve it the name of N. cinereus. 

 It is stated to be very similar to N. coucang Bodd., but the head, neck and forearms 

 are clear grey and the face markings obsolete. 



Milne Edwards also gives a drawing of this species (tom. cit. plate 3.) but that 

 plate does not resemble my specimens which are much paler as to the general colouration 

 of the fur. 



Anderson in his »Catalogue of the Mammalia in the Indian Museum », Part I p. 95 

 (Calcutta 1881) recognizes three varieties of Nycticebus tardigradus viz. cinerea, malaiana 

 and javanica. The description of var. cinerea which I here content in full fairly well 

 suits the male specimen in my collection. Anderson writes: »Clear greyish ashy or silvery 

 grey on the head and neck, with only a trace of the head-markings so distinct in the 

 Ja van race; the rest of the trunk greyish, but washed with brownish and tending to reddish 

 brown on the hind quarters. Dorsal band rich dark brown, fading away on the vertex. » 



