32 
THE VOYAGE OF H.M.S. CHALLENGER. 
Specimen from 
Somal oxea. 
Protrisene. 
Anatrisene. 
Torres Strait, 
2-85 X 0-028 
4-65 X 0-016 
5-355x0-016 
( 0-035 
4-65 X 0-024 ) 
Port Jackson, 
3-26 X 
\ 
5-8 xO-02 
( 0-047 
5-16x0-02 ) 
( 0-044 ) 
Samboangan, 
3-37 x«^ ^ 
4-65x0-016 
6-63 X 0-012 
( 0-047 ) 
The specimens are arranged in the Table in the order of their size, that from Torres 
Strait being the smallest. 
The structure of the cortex is that of the genus; the inner layer of the cortex varies 
from 0’8 to 1'9 mm. in thickness, the outer layer from 0'16 to 0‘8 mm., increasing to 
1*6 mm. in thickness, where it forms the tissue of the conules; and even to 2 '7 mm. in 
the region of the oscule where the conules are longer. 
The outer layer of the cortex consists of cavernous collenchyma, the cavities usually 
so numerous and large as to reduce the tissue to the thinnest possible films. The 
matrix, in addition to containing stellate cells (collencytes), is crowded with depressed 
oval cells, bounded by a sharply defined outer wall, and containing a vesicular nucleus 
with a spherical nucleolus, the former surrounded by granular protoplasm from which 
thin threads extend and pass into a protoplasmic film coating the inside of the wall. 
These cells occur crowded together where the collenchyma forms a dense tissue around 
the margin of the oscule, and are scattered parallel to the surface through the walls of 
the cavities of the cavernous collenchyma. Fusiform cells also are numerous in the 
collenchyma, especially where it forms the roof to the subdermal cavities, and the tissue 
of the conules. 
The outer layer of the cortex has the usual structure, but the cortical oxeas appear to 
lie more regularly radiate in it than in Craniella cranium, their distal ends extend 
into the collenchymatous floor of the subdermal cavities, and they pass through the 
conular pillars up to the skin. 
The subdermal cavities are either simple open chambers, often extending continuously 
within the outer layer of the cortex from one conule to another, or they may be broken 
up by irregular trabeculae into a number of small communicating cavities. The roof is 
formed by the skin which extends between the conules and is pierced by numerous pores, 
which either open into the cavity directly, or, when the roof is thick, by short canals. 
The oscule -is surrounded by concentric- myocytes; several excurrent canals pass 
through the inner cortex to open into the cavities of the outer cortex, and these 
finally discharge by the oscule. 
