PROF. OWEN ON THE ANATOMY OF THE INDIAN RHINOCEROS. 53 



canals (lb. m, m). The diameter of the orifice was about a line, but as the canals 

 passed inwards in the parietes of the urogenital passage, they widened to the diameter 

 of from two to three lines. At about three inches, distance from their outlet they 

 branched off into two or three smaller divisions, from which a glairy mucus could be 

 expressed, and these again subdivided and terminated in blind secerning cseca applied 

 to the outside of the commencement of the vagina. The orifice by which the vagina (/?) 

 communicates with the uro-genital canal is small in proportion to the width of that 

 canal, and its area is diminished by several short oblique longitudinal folds, whose free 

 edges project into it : the whole of this contracted orifice may be regarded as a form of 

 hymen, beyond which the vagina rapidly dilates in the wide canal represented at v, v, 

 PI. XVIII. 



Nen'ous System. 



Of this part of the Anatomy of the Rhinoceros the opportunities for making obser- 

 vations were limited to the structure of the Brain and the Eye. 



The brain of the full-grown male (PL XIX. XX. & XXI.) weighed, when deprived of 

 its membranes, 1 lb. 14^ oz. avoirdupois, its proportion to that of the entire body being 

 as 1 to 164. 



An upper view of the natural size is given in PI. XIX. fig. 1, a side view in fig. 2, 

 and a base view in Pi. XX. 



The cerebral hemispheres present a subdepressed semioval form, broader behind, and 

 narrower in front than in the Horse, and presenting fewer and larger convolutions. 

 Their disposition resembles that in the larger hoofed mammalia generally ; converging 

 from behind forwards as far as the anterior third of the cerebrum, and thence diverging 

 as they extend forwards, but in a minor degree than in the Horse or Ox. 



In the view of the base of the brain (PI. XX.), the large external crura p, and internal 

 crura q, of the rhinencephalon or olfactory gangUa, 1, 1, are shown, together with the 

 protuberance r, which lies between the two crura. The chiasma of the optic nerves is 

 shown at 2, 2 ; the infundibular base of the hypophysis cerebri at k ; the single mass 

 representing the corpora candicantia at I ; the crura cerebri at i, and the third pair of 

 nerves at 3, 3. The obtuse apices of the ' protuberantiee natiformes,' o, are less broad 

 than in the Ox, and more resemble the shape of the same parts in the Horse. 



The cerebellum shows the small lobes, called ' flocci,' at h ; and the inferior con- 

 volutions at g. The olivary tracts make a very slight prominence at d ; the pyramidal 

 bodies are better defined, but are crossed by some superficial transverse fibres near the 

 pores/: and the ' corpora trapezoidea,' e, are defined. The inferior ' vermiform process ' 

 of the cerebellum is more regular and better defined than the superior one : it is shown 

 at V, fig. 4, PL XXII. 



