338 Dr Dalton jun. on the Proteus anguinus. 



made of the difference between them. The muscular fibres 

 of the body are also very large, and very distinctly striated. 

 Their diameter varies from 0019 to *0036 inch. The nerve- 

 fibres were not remarkably large, those from the facial measur- 

 ing only -00027 inch in diameter. 



The two most interesting peculiarities of the animal, taken 

 in connection with its subterranean mode of life, are the 

 colourless condition of its skin, and the imperfect develop- 

 ment of its visual organs. At first, the eyes seem to be al- 

 together wanting ; but, on close examination, they may be 

 discovered, in the recent state, as two minute blackish points, 

 situated about the junction of the anterior and middle thirds 

 of the head. When the animal has been preserved in spirits, 

 it is sometimes impossible to distinguish them until the in- 

 teguments have been removed. They are then found lying 

 immediately beneath the skin, imbedded in a small quantity 

 of adipose tissue. In an individual measuring 8f- inches in 

 length, the eye-ball was g^th of an inch in diameter ; and the 

 optic nerve, just before joining the globe, a^d of an inch. 

 Notwithstanding its minute size, however, the eye is suffi- 

 ciently well developed as to its structure. The sclerotic is 

 covered with brownish spots, mostly hexagonal in shape, and 

 which are more thickly crowded and deeper in shade just at 

 the margin of the cornea, where they form a blackish ring. 

 The crystalline lens is globular, and T \ ¥ th of an inch in diame- 

 ter. There were some appearances of a nearly colourless 

 iris lying behind the cornea, but the parts were so minute 

 that I did not succeed in ascertaining its existence by dis- 

 section. The brain is pretty well developed, though less so 

 than in other allied genera ; and notwithstanding the imper- 

 fect condition of the eyes, the lobes which, in the brain of 

 reptiles, are usually considered as representing the Tuber- 

 cular Quadrigemina, are of very considerable size. The 

 brain of the Triton cristatus, another naked amphibian, with 

 large well-developed eyes, differs from that of the Proteus 

 simply in being rather larger in comparison with the size of 

 the animal, and in having a somewhat greater proportional 

 development of the hemispherical lobes. The following are 

 the longitudinal measurements of the brain of a Triton cris- 



