46 Zoological Society. 



Reflecting on the subject, I thought it worth while to examine with 

 some care the eyes of the common Mole, an animal that spends the 

 greater portion of its time beneath the surface of the earth, and seems 

 in its general organization specially adapted for a subterraneous life. 



I shall chiefly notice what, in the dissections I have made, appears 

 to be peculiar. 



The first peculiarity that arrests attention is, that the eyes of the 

 Mole are not contained in bony sockets, but lie unprotected by any 

 bony prominences in the cellular tissue, beneath the common integu- 

 ments ; and, in consequence, were this animal an extinct one, and its 

 skeleton found in a fossil state, there being no orbit, the palaeontolo- 

 gist might be led to infer that it is a species destitute of eyes. 



The next peculiarity I would mention is in regard to eye-lashes. 

 These too it seems to" be destitute of. The hair in which the eyes 

 are buried, and by which they are defended, seems to be the common 

 fur of the head. I could detect in that immediately surrounding 

 them no hairs of larger dimensions, or in any respect difi'erent from 

 those of which its fine fur is composed. 



The apertures for the admission of light constitute another pecu- 

 liarity. When the fur is removed from the skin surrounding the 

 eyes, a minute aperture appears over each, about ^ih. of an inch in 

 length when closed, and, in this state, linear and straight, but cir- 

 cular when fully expanded. The extreme margins of these openings 

 in the integuments being covered with fur, there is no well-marked 

 appearance of eyelids, — indeed, it may be a question, whether the 

 Mole, in strictness, can be said to possess these appendages. From 

 the observations I have made, I am disposed however to mfer that it 

 does possess them, but imperfect ; — imperfect, not having been able 

 to detect beneath the marginal cutis any vestige of ciliary cartilages, 

 and yet having found in the surrounding subcutaneous cellular tissue 

 muscular fibres so arranged as if designed for closure, resembling an 

 orbicular muscle, and probably designed for and performuig the part 

 of such a muscle. 



As to the other muscles of the eye, one only, an abductor, was 

 distinguishable from adjoining muscles. It is of large size compara- 

 tively, and it may be inferred powerful : by acting on it, seizing it 

 with a forceps, and drawing it upwards, the ball of the eye was re- 

 tracted, thus denoting its office. I sought in vain for other muscles. 

 That they were not discovered, supposing them to exist, is not sur- 

 prising, considering the smallness of the organ and its peculiar un- 

 insulated position, most unfavourable for discriminating the subordi- 

 nate parts pertaining to it, such as the muscles. 



Relative to the constituent parts of the organs themselves, except- 

 ing their delicacy and minuteness, I am not aware of any peculiarity. 

 The eye-ball is about J^th of an inch in diameter; the iris dark 

 brown ; the pupil circular ; the lens about j-g^rd of an inch in dia- 

 meter. Traces of a vitreous humour, and also of an aqueous, were 

 observable ; the former in the appearance of a cellular texture, as seen 

 under the microscope with a high power ; the latter as an exudation 

 of moisture, a just perceptible quantity of fluid, when the ball was 



