Zoological Society. 517 
apparently i in connection with disease; and their size and shape are 
undoubtedly liable to modifications, from the effect of causes which 
have not yet been clearly explained. The observations recorded in 
this paper have been made with so much care, to obviate any source 
of fallacy, that I am disposed to place much confidence in the results ; 
but even if it should ultimately appear that the differences which I 
have described are not permanent, but merely within the limits of | 
variation to which the blood-disks are liable, this would be some 
addition to our knowledge of these curious bodies, and would, at all 
events, be sufficient to reconcile the numerous discrepancies appa- 
rent in the measurements of various eminent observers. 
““In conclusion, it may be remarked, that however paradoxical 
the history of the red particles may be, still, that of the blood gene- 
rally is in many respects equally so. As we can only expect to ob- 
tain a knowledge of the physiology of the corpuscles by the multi- 
plication of observations, it is especially desirable that persons re- 
siding abroad should avail themselves of opportunities of examining 
the blood of such animals as are not easily to be seen alive in this 
country. Among the birds, it may be mentioned that an examina- 
tion of the blood of the different species of ‘Temminck’s orders Ani- 
sodactyli and Inertes is especially required ; and when made, it is not 
improbable that some interesting results may be obtained.” 
June 23.—William Yarrell, Esq., V.P., in the Chair. 
Mr. Ogilby characterized a new species of Monkey, under the 
name of Papio ochreatus. ‘‘I1 saw this animal” (observed Mr. 
Ogilby) “‘ in a travelling collection last June. It was of a uniform 
dull black colour on every part of the body, both above and below, 
except the arms and legs, from the paws to the elbows and knees, 
respectively, which were dark gray, as was likewise the space be- 
tween the scrotum and the callosities; the scrotum itself was dirty 
flesh-colour ; the face and ears naked and black ; the naked part of the 
hands and feet brown, and there was a large naked patch, of the 
same colour, surrounding the callosities ; but whether natural, or the 
effect of accident, Iam unable to determine. The ears were rounded, 
and less pointed than in the Papios generally ; the countenance re- 
sembled that of the Pig-tailed Baboon (P. Nemestrina), but the face 
was more attenuated; size that of the Pig-tail. I was unable to 
learn whence the individual here described had been obtained. It 
constitutes a very distinct species, and may be characterized as fol- 
lows :— 
- The Booted Baboon, Parro ocHREATUS: P. supra subtusque niger, 
brachiis et cruribus canis.’ 
A species of Trionyx, or, according to MM. Dumeril and Bibron, 
Gymnopus, was exhibited. This specimen had lived for some time 
in the Society’s menagerie, having been sent from the Euphrates by 
Colonel Chesney. 
. The following description and observations relating: to this animal. 
were communicated by Mr. Martin :— 
