Zoological Society. 517 



apparently 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. " I 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, I am 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, Papio ochreatus ; P.supra subtusqueniger, 

 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 :-— 



