1872.] DR. J. ANDERSON ON MACACUS BRUNNEUS. 21 1 



tail. The first four have a little more than one inch of antero- 

 posterior extension; while the last five, being very minute and 

 doubled to the left side as a hook, only extend one line and a half 

 in length. The spinous process of the first caudal is reduced to 

 a minute nodule ; while it is more strongly developed in the second 

 and third, preserving, however, the same character that it does in 

 the first, and it is altogether lost in the fifth caudal. 



The pedicles supporting the anterior zygapophyses are long and 

 strongly developed on the first caudal ; but they gradually become 

 smaller as they are traced to the fourth, and in the fifth they are 

 simple nodules. The anterior and posterior pedicles of the fourth 

 and third vertebra do not touch each other. The posterior zyga- 

 pophyses of the third caudal are very small diverging processes, 

 which disappear on the fourth vertebra as a minute eminence at the 

 extremity of a ridge which is serially homologous with the pedicles 

 of the anterior zygapophyses of the anterior caudals. The sixth 

 caudal is a simple ossicle, nearly 2 lines in length ; and the seventh 

 is reduced to about one third of its size. The eighth caudal vertebra 

 is a minute ossicle, placed to the right of the axis of the spinal column, 

 with the ninth vertebra slightly to the left of its posterior end— the 

 tenth and eleventh vertebral ossicles being placed transversely, from 

 right to left. 



In life the tail is rarely carried erect, and is, as a rule, applied over 

 the anus, its latter fourth being doubled upon itself to the left, and 

 serving to fill up the interspace between the upper divergent portion 

 of the callosities ; so that the animal sits on this portion of its tail, 

 the upper surface of which is rough and somewhat callous. The 

 latter fourth of the tail contains the hook-like process formed by 

 the last caudal vertebrae ; but they are restricted to its base — the re- 

 mainder of the organ being tough and tendinous, aud destitute of 

 vertebral elements. Here, then, is an instance of a Monkey sitting 

 on its tail ; and although it may be that it does not invariably do so, 

 I am prepared to state, after careful observation, that it does so very 

 frequently ; and there is the more importance to be attached to this 

 observation, because this habit appears to be a peculiarity of the 

 species. 



Associated with this habit, we find a tail with its latter fourth 

 bent upon itself and applied between the callosities, and its upper 

 surface roughened by being sat upon ; and moreover we find, when 

 we come to examine its structure, that this bent portion contains 

 only a few rudiments of vertebra at its base, its greater extent being 

 reduced to a tendinous mass. These facts seem to have only one ex- 

 planation : this tail, from its short size, is in the Monkey's way when 

 it sits down, and frequently becomes placed under the animal while 

 it is in this attitude ; and from the circumstance that it does not ex- 

 tend beyond the extremity of the ischial tuberosities, it seemsas if 

 the tail originally had been bent round, by the will of the animal, 

 into the interspace between the callosities to escape being pressed 

 between them and the ground, that, in time, the curvature became 

 permanent, fitting in of itself when the organ happens to be sat upon. 



