158 



Professor Harrison read a paper on the Anatomy of the 

 " Lachrymal Apparatus" in the Elephant. 



" In no part of the animal economy has more curious and 

 interesting diversity been displayed than in the structure and 

 arrangement of the several ' tutamina oculi,' which constitute 

 the lachrymal and palpebral apparatus. In aquatic beings 

 the surrounding element renders these appendages in general 

 unnecessary, and therefore, among them they are almost 

 universally dispensed with, although we occasionally meet 

 with some part of them in a rudimentary form ; thus among 

 the Cephalopodous MoUusca, the Octopus has the voluntary 

 power of drawing the skin over the front of the eye, and in 

 other species it is continued over this organ. Among the 

 Gasteropods, the well-known tentacles in the Umax admit of 

 the eyes being retracted within the cutaneous tube, like the 

 inversion of the finger of a glove, and are thus protected from 

 external injury. 



" In Fish the lachrymal apparatus is wholly absent, and the 

 palpebral most generally so ; but in some the skin passes over 

 the forepart of the eye, without forming any fold ; in others, 

 there are slight duplicatures, more like eye-brows than true 

 palpebrae ; many of the osseous fishes have a small vertical 

 fold at each canthus which can form a partial covering, and 

 in the Tetraodon Mola the eye can be completely covered by 

 an eye-lid which has a circular aperture capable of being 

 closed by a sphincter muscle, and opened by five radiating 

 muscles attached to the bottom of the orbit. ( Cuvier^s Anat. 

 Comp., tom. ii. p. 434.) 



" In the Reptilia both the lachrymal apparatus and the 

 palpebrae are present, but very diflferently modified in the dif- 

 ferent classes. In Birds the whole arrangement is most com- 

 plete, there being three palpebrae, a lachrymal apparatus, and 

 the gland of Harder. 



" In Mammalia there is great diversity in respect to these 

 organs. In Man and Quadrumana the palpebrae are very per- 



