304 NEW YORK STATE MUSEUM 
ural cavity without any adjacent hypodermal cells. Such a 
cavity is represented on plate 28, figure liccp in cross sectiom 
and at figure 8ccp in longitudinal section. In the latter case it 
will be noted that the cavity is continuous with the ventrak 
cavity of the dorsal spines described above. In the drawings 
representing the epithelium surrounding the cuticular pocket, 
the outlines of the cells are not shown, because they could not 
be made out with certainty on the preparations. Because of 
the necessity for determining the homology of the threads of 
protoplasm extending between the lamellae of the cuticular 
pocket, whether more than a single thread arose from a single 
cell, which could not be done, it was thought best to leave out 
the cell boundaries. The preparations represented by the 
drawings give one the impression that we have to do with 
a syncytial structure, but it is not improbable that more care- 
fully fixed material would show cell outlines. As it is almost 
axiomatic that, wherever cuticular structures are found in the 
Hexapoda there are epithelial cells closely associated with the 
cuticle from which they are derived, an explanation of the con- 
ditions existing here is thought necessary. The hypodermalk 
cells, where they are adjacent to the cuticle and where they 
inclose the cavity, are long and well marked, while the cavity 
is filled with a homogenous, lymph-like staining structure. The 
Specimens studied were not originally intended for histological 
study; the entire larvae were dropped into hot water and thence 
into either hot Perenyi’s solution or hot vom Rath’s picro-: 
Sublimate. The first impression on studying this structure 
was that it was an artifact due to improper fixation. But, 
when several series had been examined and it was found that 
the location and extent of the cavity was practically the same 
in all, this explanation had to be given up as improbable. The 
distance of the cuticle from the hypodermal cells sets aside 
the possibility of its always having been a cavity and that the 
structureless substance within the cavity is blood, because, if 
accepted, we have to meet the more difficult problem of ex- 
plaining how the cuticle adjacent to the cavity could have been 
—— aE 
