^22 Charles R. Stockard 



INCOMPLETE DIPROSOPUS WITH THREE EYES AND ONE 

 ADDITIONAL LENS 



A most valuable object for study was an incomplete diprosopus 

 monster which appeared in my solutions. This individual had 

 two heads separated as far as the lateral eye region. It appeared 

 as indicated by Fig. 21 when seventy-two hours old. The two 

 brains are separate, almost back to the auditory vesicles. Two 

 normal eyes are shown in outer lateral positions while between the 

 heads one eye, perfect in shape, is mated with the outer eye of the 

 left head and a circular body occupies the usual position of left 

 eye on the right head. The embryo seemed normal in other 

 respects and was in a vigorous condition. 



The monster when eighteen days old had developed to the usual 

 size and was still hardy. At this time it presented a striking 

 appearance as indicated imperfectly by Fig. 22. Three large 

 eyes normal in form and capable of movement looked out from the 

 double head. All visible evidence of the circular body shown 

 near the middle eye when seventy-two hours old had disappeared. 

 The middle eye was clearly paired with the left eye of the left head 

 component and the right eye of the right head seemed mateless. 

 A single pair of auditory vesicles were present. The young fish 

 respired and twisted vigorously within the membrane. Three 

 hours after this drawing was made, the embryo hatched and swam 

 about in a circular fashion, the body not straightening perfectly. 

 The free living animal was kept for five days and then preserved 

 for sectioning. 



The sections show the presence of two brains, one spinal cord 

 and one normal mouth leading into a pharynx with its series of 

 gills, while a second short throat is present in the right head. There 

 are two notochords back to the middle of the yolk-sac and one from 

 there on. The rear end of the medulla becomes single and only 

 one pair of ear vesicles are present. There are two olfactory pits 

 anterior and median to the lateral eyes. 



Three perfectly normal eyes exist. They possess clearly dif- 

 ferentiated retinae, irides, humor chambers and lenses. Two of 

 these eyes are connected in the usual way with the brain of the 



