36 MR. R. I. POCOCK ON THE EXTERNAL 



form a single long pad which sometimes fuses proximally in the 

 middle line with the external proximal, which is itself united to 

 the external intermediate, forming a long pad extending along 

 the outer edge of the sole of the foot. The second and thii-d 

 intermediates are united to form a single large elongated pad, 

 broad distally, narrowed proximally, whei'e it terminates in the 

 middle of the membranous area of tlie sole. Of digits two to five 

 the fourth is the longest as in Lemuroid Primates; but the third 

 has an erect claw like the second — a characteristic not found 

 in any Lemuroids, but probably primitive and forcibly recalling 

 the con-esponding " syndactyle " digits of many Marsupials (text- 

 fig. 9, D). 



The Suhlingua. 



There are one or two points to be recorded in connection with 

 the suhlingua, an organ which is especially well developed in the 

 Lemuroid Primates. Typically it is a thin flat fibrous plate, 

 lyrate or leaf -like in form with free apex and free lateral margins. 

 It covers a considerable area of the lower surface of the tongue, 

 the frenum of which arises from an angular notch in the middle 

 of its posterior border. The pointed or truncated apex is ser- 

 rated or denticulated to a varying extent, and the underside is 

 strengthened by a fine median longitudinal ridge, with frequently 

 a smaller ridge close to it on each side, making three in all. 



Beneath the sublingua the floor of the mouth is provided in 

 front with a pair of small soft flaps, the frenal lamellce, arising 

 at the bottom of the lingual frenum and continued backwards to 

 a varying extent as a free nari-ow edge towards the base of the 

 tongue. A similar and homologous structure is pr( sent in some 

 other Mammals — e. g., Canis, Pteropus, where, as in the Primates, 

 it overlies the orifices of the sublingual and submaxillary salivary 

 glands. 



In the species usually referred to Lemur the sublingua ex- 

 hibits certain structual differences, which examination of a larger 

 number of individuals than I have seen may show to have 

 systematic value. For instance, in L. variegatus there are 

 three comparatively strong denticles at the tip and three corre- 

 spondingly strong keels below. In other species the tip is x-ather 

 serrulate and the keels weaker. On the_ other hand, I have noticed 

 differences in the shape of the sublingua within specific limits. 

 In a male of L. coronatit.s^ for example, it was lyrate witli bulging 

 postero-lateral margins ; in a female it was evenly attenuated, 

 the two margins gradually converging from near the base to the 

 tip. In the male again the frenal lamellae formed together a 

 broad semicircular flap ; in the female they were narrower, 

 forming a nearly parallel-sided flap. In a, male specimen of 

 L. cdhifrons alhifrons and in a female of L. a. nigrifrons the 

 frenal lamellaj were of the same shape as in the male L. coro- 

 natus ; but in examples of L. variegatus, macaco, catta, and mongoz 

 the laraellte were narrow and resembled more or less closely those 



