454 MR. F. E. BEDDARD ON HAPALEMUR GRISEUS. [JlUie 16, 



to be visible as a fold a line may be traced running to the larger of 

 the two lateral folds, to which the attachment of the anangious fold 

 is more closely approximated. 



Cheirogaleus {Microcebus) smithi. — This Lemur agrees closely 

 with Galago. The median anangious fold arising from the small 

 intestine is very large ; there is only one lateral fold bearing a 

 ))loo(J-vessel, which fuses with the median fold ; this lateral fold 

 arises behind the small intestine from the ileo-colic mesentery ; the 

 same is probably true of Galago, though my specimen did not 

 show it. 



Of the genus Lemur I have examined the following species, viz. 

 L. brunneus, L. ruffrons, L. albifrons, L. varius, and L. anjuanensis. 



In Lemur brunneus there are only two folds attached to the 

 caecum ; one of these extends to the very extremity of that append- 

 age, arising not from the small intestine, but from the mesentery 

 behind the small intestine which attaches it to the colon ; this fold 

 bears a blood-vessel ; the second fold is very short and apparently 

 completely anangious ; it arises from the small intestine itself and 

 is attached to the first-mentioned fold, so that there is but one line 

 of attachment to the caecum ; the attachment of the second (anan- 

 gious) fold to the first is for a distance of not more than one fifth of 

 its length. 



Lemur rvfifrons appears to be exactly like the last species in the 

 number and disposition of the mesenteric folds attached to the 

 csecum. 



Lemur albifrons differs from the last two species only in the 

 reduction of the anangious fold arising from the small intestine. 



In Lemur varius this fold is still further reduced and has become 

 quite rudimentary. 



Lemur anjuanensis, as regards the folds (see fig. 3, p. 455), is 

 precisely like Lemur brunneus. 



As regards the disposition of the folds of mesentery connected 

 with the csecum, the genera mentioned in the present paper appear 

 to fall into three groups : — 



(1) Hapalemur stands apart from the rest in possessing only the 

 two lateral folds, both of which bear blood-vessels. 



(2) In Lemur, Galago, hr)d Microcebus (= Cheirogaleus) only one 

 of the two lateral, vessel-bearing, folds is present ; in addition to 

 this there is an anangious fold arising from the ileum and inserted 

 on to the lateral fold. 



(3) In Loris, Ngcticebus, and Perodicticus all three folds are 

 present, but one of the lateral folds is generally much more developed 

 than the other. The median frenum may (Ngcficebus) or may 

 not (Perodicticus) be attached to the larger of the two lateral folds. 



It might be supposed that the raison d'etre of the persistence of 

 the median frenum was to assist in preventing the displacement of 

 the caecum ; the short sac-like caecum of Hapalemur, which is 

 without the median frenum, might, on account of its shape and 

 relative size, be less easily displaced or bent than the elongated 

 caecum of Lemur or Perodicticus. 



