Alt—Histology of the Hye of Typhlotriton Spelaeus. 85 
degeneration of the eyes of the Missouri Cave Salaman- 
der, ete.’’ Biological Bulletin, 2:1. 1900. 
In this paper the eyes of Typhlotriton spelaeus from 
Rock House Cave and from Marble Cave, Mo., are de- 
scribed very exhaustively. Again it appeared strange 
that in this paper I could nowhere find any reference 
whatever to the former paper, although the two descrip- 
tions differ so widely, as will be seen from the follow- 
ing summary with which this second paper ends: 
‘‘Typhlotriton is an incipient blind salamander liv- 
ing in the caves of southwestern Missouri. It detects its 
food by the sense of touch without the use of its eyes. 
It is stereotropic. The eyes show the early stages in 
the steps of degeneration from those of salamanders liv- 
ing in the open to those of the Typhlomolge from the 
caves of Texas. The lids are in process of obliteration, 
the upper overlapping the lower so that the eye is always 
covered in the adult. The sclera possesses a cartilagin- 
ous band in the larval stage but not in the adult. The 
disappearance of the cartilage is probably an incident 
of metamorphosis, not of the degeneration the eye is 
undergoing. The lens is normal. The retina is normal 
in the larva with a proportionately thicker ganglionic 
layer than in the related epigaean forms. Marked onto- 
genetic degenerations take place during and shortly after 
the metamorphosis. a. The outer reticular layer dis- 
appears. b. The rods and cones lose their complexity 
of structure, such as differentiation into inner and outer 
seements and finally are lost altogether.’’ 
In this paper the author also states ‘‘that the six eye 
muscles are present.’’ 
After I had read the present paper before the Acad- 
emy of Science, I was made acquainted through the kind- 
ness of Miss M. Klem with a large and beautifully illus- 
trated volume, entitled ‘‘The Cave Vertebrates of Amer- 
ica. A study in degenerative Evolution,’’ by Carl H. 
Kigenmann. Published by the Carnegie Institution of 
Washington, D. C., June, 1909. 
