56 
the foot-cavity densely filled with blood-corpuscles, but the inter- 
vals between the folds of the intestine contain a very large amount 
of them. In some sections this may occasion the apparent pre- 
sence of two ventral sinuses, one above the other, and separated 
by the diaphragm: the illusion is due to blood penetrating between 
the diaphragm and the folded wall of the intestine. As the latter 
is not always closely applied upon the diaphragm (fig. 24) this 
very often happens and when in a series of sections the ventral 
sinus happens to be empty it might lead to confusion. Similar 
local dilatations, occasioned by accumulation of blood-corpuseles, are 
encountered in the dorsal bloodvessel; from the heart these are 
easily distinguished by the nature of their walls. 
The lacunae in all other tissues are both numerous and well 
filled. Such is the space between the pharynx and the body-wall, 
the sheath enclosing the salivary glands, the distinet longitudinal 
lacunae (without separate cellular elothing however) in the foot- 
gland, in the connective tissue (fig. 23, L) ete. In the hinder ex- 
tremity of the body a sort of spongy arrangement obtains around 
and behind the posterior opening of the generative gland and in- 
testine by the numerous transverse and other fibres cerossing the 
body-cavity from one outer wall to the other, and these spaces 
too are partially filled with blood-corpuscles. 
It is in this region that all investigators place the respiratory 
apparatus of Neomenia. Korkx and DanIELssen (17) describe it 
as follows: „At the posterior extremity, likewise towards the ven- 
tral surface there is also a fissure in the mantle which can expand 
and coniract and forms the proper entrance to the branchial cavity. 
This is ovate from behind forwards. ..... The branchiae are 
arranged in the form of an oblong eirelet consisting of thirty fili- 
form tubules, of which those nearest the back are the largest, 
and those towards the ventral surface are extremely short.” In 
Prof. Ray LANKESTER’s specimen I find the apparatus correspon- 
ding in situation and in the details of its structure to this descrip- 
tion. Moreover the communication between the heart and the 
branchial apparatus may here be distinetly observed. 
