PLATANISTA. 469 



muscles (m) are distinctly visible so that the lids must be somewhat moveable, 

 though to what extent it is difficult to say. 



Tracing the palpebral conjunctival membrane, its cylindrical marginal epithe- 

 lium is readily followed into the re-entering angle of the eyelid, as it passes on to the 

 cornea. In the angle, it has quite a papillary character, which is lost on the corneal 

 surface. The corneal conjunctiva is nevertheless easily demonstrated, its free epithelial 

 layer assuming a flattened compressed stratified scaly character. This outer layer 

 is relatively of moderate thickness and passes insensibly into a deeper well-defined 

 layer of spheroidal or vertically disposed oblong epithelium. This layer is further 

 and notably distinguished by possessing a series of mucous glands which dip down 

 on to the face of the cornea. These glands are simple and tubular, a few slightly 

 racemose in character; most being long, but some intervening ones shorter. 

 They are filled throughout with nucleated epithelial cells and granules. The 

 submucous connective tissue between the glands and the more fibrous structure 

 of the cornea itself, form papillae which dip between the glands and in which, I 

 believe, could be traced minute capillary and nervous twigs, and, in more than one 

 instance, I observed an oval body possessing characters resembling the so-called 

 "tactile corpuscles" of the human skin. 



Indeed, the structural resemblances of the conjunctiva to the skin in Tlcda- 

 nista are close, save the great quantity of dark pigmentary matter in the latter. 

 If these observations be correct interpretations of the nature of the conjunctiva, 

 they will go a considerable length towards the maintenance of the idea that the tactile 

 natm^e of the front of the eyeball may, to a certain extent, supply the absence of 

 power in the visual apparatus. Whether further investigations will support such 

 a theory remains for future substantiation and more extensive examination. 



The cornea proper equals in thickness the layers of conjunctiva above referred 

 to. Throughout, it appears to consist of wavy elastic fibres, elongate or fusiform 

 corpuscular ceUs, and ordinary connective tissue. The fibres are most dense inter- 

 nally and looser towards the conjunctiva. I feel by no means clear as to the 

 presence of a posterior elastic lamina, the so-called membrane of Demours. At 

 the junction with the iris, a film of transparent cells could be distinguished, but 

 in none of my sections did this extend any distance beyond. 



The eyeball, as a whole, has a pyriform shape, the blunt end being forwards. The 

 very open condition at the entrance of the optic nerve suggests, of itself, imperfect 

 development. The sclerotic coat is in close union with the choroid, and the former 

 is tolerably uniform in its thickness, nowhere having any great depth. Its outer fibres 

 mingle with the connective tissue of the surrounding cushion of large fat-cells, and 

 its inner fibres, in commingling with the choroid, have patches of pigmental matter 

 distributed amongst them. 



The outer division of the choroid is thus somewhat indistinct from the sclerotic, 

 though, in microscopic sections, the retinal border is as well defined as in the fresh 

 eye. The pigment cells are sparse, except quite posteriorly, where they become more 

 numerous ; but a somewhat full vascular supply is evident, even by observation on 



