604 
ZOOLOGICAL LITERATURE. 
by the acoumulation of blood-corpuscles in tbe various parts of 
the system: though this method be laborious, yet the results 
are satisfactory, as in such natural injections there is very little 
danger of being deceived by the blood having become extra- 
vasated from its natural channels. The blood-system may be 
looked on as closed ; the blood-channels arc well defined, but it 
is not easy to determine whether or not they are ])rovided with 
proper walls ; tlie heart is tubular. In addition to the tu o great 
branchial channels, the dorsal and ventral (which communi- 
cate with each other through the numerous transverse chan- 
nels of the branchial sac) , the blood-circle is rendered more com- 
plete by tlie presence of cylindrical hollow bands (suspenders), 
which pass from the transverse branchial channels and from the 
great ventral channel to the walls of the pallia! chamber; the 
function of these bands as blood-carricrs seems hitherto to have 
escaped detection. The nervous system is in a very rudimen- 
tary condition ; there is but one ganglion, invariably placed 
between the two respiratory tubes. The relation that subsists 
between the Tunicata and Polyzoa is briefly adverted to, the 
author at present neitlier agreeing with the views of Professor 
Allman nor with those of Professor Huxley, but inclining to 
think that the branchial sac is a new and distinct development, 
as the endostyle is, and as are the oral lamina, the branchial 
tubercle, and the tentacular filaments of the inhalant tube — and 
that all these organs have equally their origin in the lining 
membrane, and have no homological representatives in the Po- 
lyzoa. This interpretation of facts leads to a belief that the 
branchial sac is the rudiment of the Lamcllibranchiatc gill. 
The ganglion in the Tunicata appears to be the true representa- 
tive of the ])ranchial ganglion in the Laincllibranchiata. This 
determination of its nature agrees well with its position, and we 
thus find in the nervous element a corroboration of the above 
suggestion as to the homological relation of the branchial sac. 
Heller, C. Die Bryozoen (Polyzoa) des Adriatischen INleeres. 
Verhandl. der k.-k. zool.-bot. Gesellschaft in Wien, Bd. xvii. 
pp. 77-136, and Tafeln; also separate reprint, Wien, 1867, 
pp. 1-60, Taf. 1-6. 
In this catalogue of the Polyzoa met with in the Adriatic 
Sea, Professor Heller enumerates 85 species of Cheilostomata, 
27 of Cyclostomataj UniX 6 of Ctenostomata. Several new genera 
and species are described. Figures of the new species are given. 
Tables of the bathymetrical and geographical distribution of 
the species are appended. 
Hyatt, A. Observations on Polyzoa. Suborder Pbylactolse- 
mata. Communications Essex Institute, vol. v. (Nov. 14, 
1866) pp. 97-112. 
'J'hcse ob^ei'VRtipps chiefly anatomical, and ai’O continued 
