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XXI. On the Physiology of the Ballial Stiluses of the Brachiopoda. By Joiin t D. M 
doxald, B.N.j F.B.S. Communicated by George Busk, Esq., F.B.S. , See. Z.S. 
Read April 18th, 1861. 
1 Mr. Hancock and Professor Huxley belongs the credit of having first cast a doubt 
on the nature and office of the so-called Cuvierian hearts of the Brachiopoda ; and should 
any further evidence be required to sustain the truth of the position ultimately laid down 
by those original observers, I have to announce my discovery in Lingula, of a determinate i 
circulation of spherical and violet-tinted corpuscles (fig. 5) in all the ramifications of the 
pallial sinuses (Plate XXXV. fig. 4), not depending upon the contractions of a propulsory 
cavity, but upon the undulations of a ciliated lining. It, moreover, presented this charac- 
teristic peculiarity, that an onward and a returning current are at the same time visible in 
each canal, as shown by the direction of the arrows in fig. 4. 
The white lines which are described as running upon the outer wall of the pallia! 
sinuses of Lingula, and about which so much misconception appears to have existed in 
the mind of Vogt, are nothing more than the septa more or less perfect (fig. L, a), which 
serve to direct as well as to obviate the friction of two ciliary currents passing in opposite 
directions in the same vessels. Mr. Hancock's reasoning against Yogt's opinion, that 
these are vascular ramifications, is simple and conclusive ; but, of their real nature as just 
pointed out, I can entertain no doubt whatever. 
The four Cuvierian hearts of BhynchoneUa, singularly enough, have given place to the 
five contractile vesicles of Mr. Hancock ; and if these latter, with the vessels connected 
with them, be not really homologous with the water-vascular system of the Jnmdoida, 
the coincidence in the same animal of another and a purely ciliary circulation in which 
coloured corpuscles, developed for that special purpose, seem to perform the office of blood- 
globules, is not a little interesting. 
In some of the Beroida? the sinus system exhibits a remarkably beautiful ciliary circu- 
lation of a corpusculated fluid, and the ovaria occupy the walls of those ramified and reti- 
culated canals, so much after the fashion of those of the Brachiopod, that the homologies 
of the two systems can scarcely be doubted. There is this difference, however, that in the 
Beroidce, the main trunks of the sinuses, which form the equivalent of the common 
cavity, so called, of the true Bolypi, open directly into the stomach ; whereas this com- 
munication is altogether cut off in the Brachiopod, and the escape of the ova is provided 
for by the external openings so clearly demonstrated by Mr. Hancock in the organs pre- 
viously recognized as hearts. The question arises, Is this difference sufficient to destroy 
homology here indicated ? As well might it be said that the absence of an anal 
let to the alimentary canal of Waldlieimia militated against its homology with that of 
Lingula ; or, that the open water-vascular-system of Bistoma had no equivalent m 
the 
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