C. J. Bond 111 



failure of this pigmentary tissue to spread from its point of entrance 

 further round the globe in these abnormal cases. 



Irregular Iris Pigmentation in Animals. 



My attention was drawn to this subject by finding that out of 

 100 wild rabbits shot on a small uninhabited island in the Orkneys 

 four animals exhibited unequal pigmentation of the iris in one or both 

 eyes. 



In three animals the upper portion of the iris in both eyes above 

 the horizontal pupillary equator was blue, the animal being partly 

 wall-eyed, while the lower or lower anterior portion was deeply pig- 

 mented (duplex type). In one animal this irregularity was limited 

 to the left eye. Plate VI, figs. 1 and 2. 



It is well known that " wall " eye occurs in many species of domesti- 

 cated animals. I am indebted to Dr Sydney Turner for some interesting 

 information about " wall " eye in Great Danes. 



The wall-eyed condition, that is the simplex type of iris, may be 

 present in both eyes in the same animal or it may afiect one eye only. 



In the latter case it may affect the whole or only a portion of the 

 same iris, the remainder being of the normal brown colour or duplex 

 pattern. 



While " wall " eye is most common in the Harlequin variety of the 

 Great Dane, that is in an individual of a bi- or tri-coloured patchwork 

 pattern or piebald coat colour, it is also found in other breeds of dogs 

 such as the English Collie, especially the " marled " variety, and in 

 the bobtailed Old English Sheep Dog and I have also seen it in the 

 Dalmatian. 



It is also noteworthy that in the individual dogs that I have 

 examined the unpigmented areas frequently occupy some portion or 

 the whole of the lower half of the iris, the opposite of the condition 

 found in man. 



" Wall " eye has also been observed in piebald and in so-called 

 " skewbald " horses but not exclusively in this breed. 



This association between irregular iris pigmentation and patchy 

 Harlequin coat is important. 



Thus in the series of the 100 Orkney rabbits there were 81 of the 

 wild grey colour, the remaining 19 showed some irregularity of coat 

 pattern, five had white patches on or in the neighbourhood of the right 

 shoulder, five on the left shoulder, three white patches on one or more 

 limbs, and six had white colouration of the forepart of the body, neck 



