158 Miscellaneous. 
The portion of the corpus Bojani which lines the vascular walls 
occurs on the walls of the auricle, the oblique afferent vein, and 
the posterior longitudinal vein. This last vessel is only separated 
from the posterior half of the collecting duct of the corpus Bojanit by 
a spongy lamina or septum of Bojanian tissue, which, being pierced 
by numerous small orifices, allows of communication between the 
vessel and the collecting-duct. 
The cells constituting the Bojanian tissue are not the same 
throughout. Those of the autonomous portion and of the septum 
just mentioned are formed of a very transparent protoplasm, in 
which there are a very variable number of small green granules ; 
they have no nucleus. Those belonging to the walls of the oblique 
afferent vein and of the auricle contain, besides the green granules, 
large colourless nuclei provided with one or two colourless nucleoles ; 
they also contain colourless granules. 
The passage from the cells of the first to those of the second kind 
takes place rather suddenly, which justifies us in thinking that the 
latter are not exclusively Bojanian, but that they may also fulfil 
other functions. 
The cavity of the pericardium is continuous below, by a passage 
placed in front of the oblique afferent vein, with the collecting-duct 
of the corpus Bojant. Between the passage and the collecting-duct 
there is a narrow oblique orifice which allows the passage of a liquid 
from the passage into the duct, but impedes its return in the opposite 
direction. ‘The liquid which has traversed the corpus Bojani rids 
itself of certain principles, which are received in the pericardium, the 
passage, and the collecting-duct. This last communicates with the 
exterior by a very narrow orifice, placed at the apex of a very small 
papilla, concealed behind the papille of the reproductive organs ; 
the discovery of this orifice is due to M. de Lacaze-Duthiers. The 
Bojanian collecting-canal receives in part the blood from the veins of 
the ‘‘ bosse de Polichinelle” at the level of the branchial ganglia, and 
opens posteriorly with a large posterior pallial vein, which serves as 
a canal of derivation for the blood returning from the mantle at those 
periods when the pallial circulation is very abundant—that is to say, 
during the period of reproduction. * 
The organs of respiration are multiple. They include the branchie, 
the surface of the body, and especially the inner surface of the mantle 
and the plazted or frilled organs. 
The branchiz are composed of very small filaments, traversed by 
a single very narrow canal. These branchial canals originate, for 
the most part, directly from the Bojanian tissue, others from a 
branchial afferent vessel of spongy or cavernous structure; they 
open into an afferent vessel, the diameter of which increases from 
behind forwards, and which occupies the upper margin of the free 
lamella of the branchia. This afferent vessel of the branchia receives 
in front some superficial vessels of the liver, some little veins of the 
mantle, and the veins of the buccal tentacles, and it opens into the 
anterior extremity of the anterior longitudinal vein. The branchial 
