286 Prof. Eschricht on the Gangetic Dolphin. 



in diameter, and sunk pretty deep in their small round orbits;" 

 the whole length of his specimen being 6^ English feet. That 

 this remark, made simultaneously with the announcement of the 

 existence of such an animal, scarcely should have received any 

 notice, might be excused perhaps by its not being corroborated 

 in Roxburgh's own figure ; but not so after Cuvier had completely 

 verified the remark in his researches on the cranium, especially 

 with regard to the corresponding smallness of the orbita and the 

 consequent abbreviation in the stem of the zygomatic bone, which 

 is quite unknown among any other toothed whales. Notwith- 

 standing all this, the minute size of the eye in the Gangetic 

 dolphin has escaped attention to such a degree, that even in the 

 most modern figures (Gray's and Jardine's) it is represented 

 large in comparison with other Cetacea. The materials fur- 

 nished by M. Reinhardt give the fullest signification to this pro- 

 portion, inasmuch as in Thornam's drawing the physiognomy of 

 a blind whale, which by measurement belongs to our dolphin, 

 has been for the first time completely expressed. And yet it 

 may be easily shown, that even in this the eye is not rendered in 

 its proper insignificance ; for the reduction being in the propor- 

 tion of ^, the slit for the eye — only 1 to 1|'" — should have been 

 given -i or \ ,,f , whereas it is made ^'". 



Anatomical considerations I think indicate, that the physio- 

 gnomy of our dolphin as a blind cetacean, is not in appearance 

 only, but significant as corresponding to the physiognomy of the 

 mole. The very minute eye of our animal has hitherto caused 

 but little surprise, because the eyes of whales in general have 

 been commonly considered as exceedingly small ; and this has 

 been demonstrated by examples among the colossal species, none 

 of the lesser sorts being adduced. This frequently repeated as- 

 sertion that whales have small eyes, is, in fact, nothing but the 

 expression of a rule of general application ; namely that the eye 

 (as well as the ear and brain), with equal functional develop- 

 ment, corresponds only in a very slight degree to the size of 

 the body ; but that in by far the greatest majority of species of 

 the same class — and still more in the same order and family — it 

 is limited within the bounds of a certain absolute magnitude. 

 This general rule properly applied, — and in a physiological sense 

 the rule admits of very easy solution, — it can hardly be said that 

 whales have particularly small eyes, as compared with mammalia 

 in general. Among the smaller dolphins, with a circumference 

 of body less than in man, for example in the porpoise, the dia- 

 meter of the eye is about 1" ; and it is quite consonant with this, 

 that colossal whales should have eyes only four times larger. 

 In comparison with land-mammalia, the eye of whales cannot 

 therefore be said to be absolutely small ; but only in so far, that 



