Manchester Memoirs, Vol. xlvi. {^\go2\ No. \^. 3 



from the surface of the eyeball itself, and arranged, roughly 

 speaking, on its ventral surface ; they are thus covered 

 by the skin, and owing to the opacity and shrinking of 

 the tissues caused by the alcohol, they are very rarely 

 distinctly visible in preserved specimens. In the example 

 examined by me there are nine on each eyeball, which 

 are arranged as follows : — There are three on the anterior 

 aspect {Fig. 2, 01, 02, oj), arranged in a vertical line on 

 what may be called the equator of the globe ; the lowest 

 of these is the largest, measuring about 1*5 mm. in 

 diameter ; it projects as a lenticular elevation above the 

 surface. The uppermost is the smallest, measuring 06 mm. 

 in diameter ; its surface is elevated into a kind of keel, 

 but I am not quite sure that this shape is a natural 

 •condition ; it may be due to shrinkage and pressure of the 

 overlying integument. 



J^io. 2. 



Side view of the left eyeball ; natural size. i — 9., ocular 

 organs. 



Behind and below this set are two organs, distinctly 

 smaller than the largest of them, situated rather nearer the 

 lens {Fig. i, Fig. 2, 0^, ^5), and behind these, immediately 

 below the centre of the lens, is another about the same size 

 as the uppermost of the first trio {Fig. i, Fig. 2, 06). At 

 the lowest point of the globe is another (<?7), which is 

 nearly as large as the lowermost of the anterior three 

 (1-3 mm. in diameter), directly behind this is the eighth 

 ^{08), and behind this again and somewhat nearer the 



