354 BEPTILIA. 



mucus is thick, like pus. The other gland [Harderian] is small, about 

 the bigness of a common bean, having a small duct opening on the inside 

 of the membrana nictitans. Its mucus is thinner than that from the 

 large gland, but is more slimy 1 . There are no puncta, nor sacculus 

 lacrymalis. 



The globe of the eye has four long straight muscles, as in the 

 human, but not corresponding to the angles of the lids as in the 

 human. Likewise one continued muscle round the optic nerve. There 

 are also two oblique muscles ; the superior is double at its origin, like 

 a biceps, enclosing the insertion of the abductor or levator, and is the 

 strongest, but it is not a trochlearis. The inferior has the common 

 structure. 



The globe of the eye is not a true sphere, the narrow axis being 

 between the outer and posterior parts. It has but a small cornea. The 

 anterior part of the sclerotic is bony as in fowls, [the bones being], as 

 it were, enclosed in a doubling of the sclerotic. The sclerotic becomes 

 very thick posteriorly ; or, rather it is lined with a thick spongy part 

 which is black, covered by the horny substance of the true sclerotic. 

 The optic nerve is very oblique ; it passes through the coats of the eye 

 without any contraction, and seems to terminate by a smooth end in the 

 eye ; but is continued into the retina. The retina is thick and strong, 

 and does not pass so far forward as in the human, and terminates in a 

 distinct edge. There is a strong nigrum pigmentum between the retina 

 and tunica choroides, and another between the ch oroides and scle- 

 rotic. The sclerotic is vascular. The crystalline humour is small, and 

 is nearly spherical, only a little flattened on its anterior surface 2 . Tbe 

 turtle can see [the same object] with but one eye at once. 



Of the Ear. — Behind the orbit there are four scales [placed vertically], 

 the edges of which make part of the posterior edge of the orbit ; 

 behind these there is a second row, four in number ; behind this row is 

 a third, which is more irregular, and the scales are smaller ; and behind 

 these is a pretty broad scale. Under the second scale of the third row, 

 counting upwards from the articulation of the lower jaw, lies the 

 external part of the ear. Under these scales is a thick ligamentous 

 substance, and immediately under that is a soft pulpy substance, very 

 vascular, of a cellular texture, which chiefly runs from a centre. "When 

 this is removed, we find a small oblong oval convex body with its broad 

 end forwards, of a transparent cast, and of a horny nature. This body 

 is attached all round its edge to the bones of the head, and to a strong 

 ligament that is placed upon its upper and posterior edge. This strong 



» [Hunt. Prep. Pkys Series, No. 1766.] 2 [ Ib . Nos _ 1674—1676.] 



