PLATANISTA. 449 



ductus communis clioledochus which passes in front of the gland, I have already 

 descrihed. 



Spleen. — (PI. XXXVI, figs. 8 and 9.) — This gland in Platanista appears to be 

 rather small, as in the adult it measured only 3"60 inches in extreme length by 2-25 

 inches in breadth. It is irregular in shape, and very unhke the well- formed spleen 

 of Oreella. It is much compressed from side to side, and externally it is marked 

 by a series of lobular projections. In the adult, the course of the vessels along the 

 free border is remarkable, owing to the existence of large dilatations (Pig. 9) into 

 which many crescentic orifices open, and another such sac occurred on the side of 

 the gland. These sacs, or dilatations, were filled with a grumous substance ia the 

 fresh state which I had not the opportunity to examine microscopically. The walls 

 of the sacs were lined with a serous membrane, and, in a few instances, short bands 

 like cordcB tendinece stretched across from one wall to the other in connection with 

 the orifices opening, from the spleen into the sac. These orifices were of various 

 sizes, some being as minute as a pin's point, wlnle others were fully 0'12 inch in 

 diameter. Their margins had a free fold of membrane almost valvular, and in some 

 instances an orifice so protected was found at once to divide into smaller but similar 

 openings. The largest sac had a capacity of 2 inches in length by 0'75 inch in 

 breadth. Structurally both appear to be dilatations of the veins. 



Liver. — Platanista agrees with other Cetacea in the simplicity of its hepatic 

 organ ; lobules and clefts being conspicuous by their absence. As the drawing 

 shows (PI. XXVI, fig. 10), it is almost transversely oval in figure, and very thick in 

 proportion. The position of the umbihcal fissure which is shallow, the median pit for 

 the hepatic vessels, the inferior course of the wide vena cava, and the deficiency of 

 a gall bladder, all simulate what obtains in the majority of Whales. An examination 

 of the hepatic vessels showed no signs of a rete mirabile surrounding them, which, 

 as I have noted, obtains in the short-headed dolphin Oreella. The hepatic tissue 

 itself is firm ; but otherwise presents no characteristic feature. 



In the hepatic ducts of the Flatanista are occasionally found immense numbers 

 of a small briUiantly coloured fluke, Distoma campula, Cobbold.^ 



Slow-hole : its cavity, pads, and sacs. — The blow-hole (PL XXXII, fig. 4, b) is a 

 longitudinal slit, about 2 inches in length, usually a little to the left of the mesial 

 line. In the longitudinal section of the skull, it is seen to be directed downwards 

 and shghtly backwards and outwards. At 1-20 inch from the surface it becomes fun- 

 nel-shaped, with a quadrangular outhne in transverse section. This portion at its base 

 has a longitudinal diameter of 0"40 inch, and in this locality the orifice of each 

 nostril is placed, and protected by rounded firm pads, which effectually close it. 



In general appearance (PI. XXVII, fig. 1) it differs materially from the 

 blow-hole in other Cetacea, inasmuch as the antero-posterior direction of the exterior 

 orifice and the presence of the great lateral crests of the maxillary bones suggest a 

 restriction of the aperture and passage. It is true that the spiracular cavity and nasal 

 sacs are not capacious ; nevertheless, then- hkeness to those of allied families is not 



' Joura. Linn. Soc, vol. xiii, p. 35, PI. x, fig. 3. 



i3 



