DEVELOPMENT OF THE SACCUS ENDOLYMPHATICUS 2993 
tion of the capsule, which runs between the sacs and the ganglia. 
I can mention one more important fact, namely, that no nerves 
or nerve-endings are to be found either in the calcareous sacs 
or in any part of the saccus endolymphaticus. The whole 
organ consists merely of glandular tubuli embedded in connec- 
tive tissue. 
pr.asc.an. 
1S 
Fig.15 Dorsal view of larva. (Stage VI.) g. spin., spinal ganglia; par., 
paraphysis; pr.asc.post., processus ascendens posterior; y., transverse processes 
in different stages of development. 
The above-mentioned investigator also gives a very proper 
account of the finer structure of the tubuli of the calcareous 
sacs, which I found to hold good for the tubuli lying within the 
other parts of the saccus endolymphaticus. He states that 
these tubuli are lined with a single-layered epithelium, whose 
cells, in transverse section, are almost square and measure about 
14 or 15y in diameter. Some of the cells, however, are cylindri- 
