90 
CHARLES L. BOULENGER. 
considerably thinner than the outer and devoid of any kind 
of sheath ; the nerve-fibres seem, however, distinctly separate 
from the bases of the overlying ectoderm cells. 
4. The Histology of the Manubrium. 
GiintheFs account of the histology of this important organ 
is somewhat incomplete and, moreover, differs in several points 
from my own observations. I have, therefore, dealt with the 
subject somewhat fully, as it seems of considerable import- 
ance to solve (as far as is possible from the examination of 
preserved material) the interesting problem of the nutrition 
of Limnocnida. 
For the purpose of description the manubrium can be con- 
veniently divided into three regions, which differ markedly from 
one another. These are — (1) an oral region in the neighbour- 
hood of the mouth; (2) a middle region, from the ectoderm of 
which medusa-buds are formed; and (3) a proximal or basal 
region. It must be understood, however, that there are no 
definite boundaries to these regions, and that each one passes 
gradually into the next. 
(i) The Oral Region. 
The distal part of this region is somewhat contracted 
in the specimen which I examined, and is coiled up towards 
the subumbrellar surface of the manubrium (fig. 1) ; this, 
however, may be only a “ post-mortem ” phenomenon. 
The structureless lamella of the whole oral region is some- 
what thicker than elsewhere on the manubrium, but the chief 
peculiarity is to be found in the structure of the endodermal 
lining. The cells constituting the endodermal epithelium are 
of two kinds : (a) long narrow cells with finely granular 
protoplasmic contents and basal nuclei (fig. 4, end.), and ( b ) 
large goblet-cells wedged in between the former and occurring 
in large numbers ( gobl . c.). These cells are very conspicuous, 
and resemble in every respect the goblet-cells of the alimentary 
