LEMURIDAE. 651 



There are no air-sacs or cheek-pouches. There is often a 

 suhlingua. The stomach is simple, the caecum large but with- 

 out vermiform appendix. In many forms the arteries and 

 veins break up into retia mirabilia as in some edentates and 

 cetaceans. 



The uterus is bicornuate and the placentation diffuse and 

 nondeciduate (except in Tarsius). There is a scrotum, and 

 the penis is pendent and usually has a bone. The urethra 

 traverses the clitoris. There are usually a pair of mammae 

 on the thorax, but there may be in addition one or two pairs 

 on the abdomen. 



The lemurs are frugivorous or omnivorous animals and are 

 all arboreal. Most of them are nocturnal. There are about 

 50 living species, 35 of which are confined to Madagascar and to 

 neiglibouring islands. The rest are found in Africa and the 

 Oriental region. 



The sub-order dates from the Lower Eocene of Europe and 

 America, but no representatives of living families are known 

 earlier than the Pleistocene. 



Fam. 1. Lemuridae. Dentition usually » f c i p ~ 3 m f ; upper 

 incisors two on each side, vertical, small and separated by an interval 

 in the middle line ; upper canines are canine-like and projecting ; lower 

 incisors close-set, laterally compressed, proclivous, and the canines are 

 closely applied to them and similar in form and direction. Premolars 

 sharp, usually with one cusp, but the last may be molar-like. P 1 on 

 the lower jaw is cam'ne-like, but bites behind the upper canine. Molars 

 with three or four sharp cusps, connected by low ridges. The orbit is 

 closed, but not shut off from the temporal fossa. The digits of both 

 raanus and pes, except digit 2 of the pes which has a claw, have flat nails ; 

 both poUex and hallux are opposable. 



Sub-fam 1 Indrisinae. iyc|p|m|; milk dentition 

 i \ c \ m \, dm 1 not being replaced ; digits 2-5 of the pes united 

 by a membrane as far as the end of the first phalanx ; tail variable, 

 pinna usually small. The hind-limbs are greatly developed, and 

 when on the ground they walk on their hind legs, holding their arms 

 above their heads. Colon spirally coiled, caecum large. Two 

 pectoral mammae. Herbivorous. Confined to Madagascar. Indris 

 Geoff. , with moderate ears and reduced tail, carpus without centrale, 

 upper incisors sub-equal, upper canine larger than p 1, 1 sp. Pro- 

 pithecus Benn., short ears, long tail, a centrale in carpus, outer upper 

 incisor smaller than the inner, upper canine larger than p\, 4 sp. 

 Avahis Jourd., ears small, tail long, no centrale in carpus, outer 

 upper incisors larger than inner, upper canine and p 1 almost equal, 

 1 sp. 

 Sub-fam. 2. Lemurinae. Dentition usually t f c -} p f m ^ ; 



