CONCHIFERS. 711 
plates described are gills, Bosanus entirely recedes ; he thinks that 
the only office of these organs is the custody of the eggs, whence 
he does not name them gills, but brood-receptacles (Bruthilter). 
Accordingly he has described an entirely different organ, not 
" noticed previously, as a respiratory organ’. According to his ob- 
servations the venous blood, that flows back from the organs of 
the body, is conducted to an elongated venous sinus situated at 
the dorsal surface beneath the heart. Close to this sinus are 
two spongy, dark-green or brown sacs, which are very rich in ves- 
sels, and receive all the blood from the venous sinus. BoJANUS 
was of opinion that these organs serve for respiration, and are 
lungs; from each sac arises a single vascular stem, which runs 
along the two gills of its own side. From the parts which BoJANuS 
names lungs, come also some short vessels, which run immediately 
to the heart, but the greater part of the blood that flows in them 
goes to the two vascular stems of the gill-plates. 
The investigations of Bosanus have made us much more accu- 
rately acquainted with the circulation of the blood in Lamelli- 
branchiata, than what had previously been written upon it. The 
mode, however, in which this anatomist explained what he observed, 
is exposed to many objections. If his opinions be not adopted, it 
is not clear what appellation ought to be assigned to the organs 
described by Bosanus. At the present day it seems that these so- 
named lungs are very commonly regarded as kidneys’. On this 
supposition, however, it remains unexplained why they receive 
all the venous blood of the body. This circumstance deserves 
special consideration, whenever a conclusion is attempted con- 
cerning the nature of these organs. Hence it is that I offered, 
now more than twenty years ago, the opinion that these so- 
called lungs are venous sinuses, as much as the part that lies 
between them, which Bosanus himself named snus venosus ; they 
Animals, p. 283. Also in Lucina and Corbis VALANCIENNES found only a single gill 
on each side ; Comptes rendus, 9 Juin, 1845, 
1 L. H. Bosanus Sendschreiben & Mr le Chevalier G. DE Cuvisr tiber die Athem- und 
Kreislaufwerkzeuge der zweischaaligen Muscheln % nsbesondere des Anodon cygneum. 
Mit abbildungen, 4to. (Printed separately from OKEN’S Tsis in 1820, Heft 7). Pout 
speaks in different parts of his work of this organ, under the name of viscus testaceum, 
2 TREVIRANUS Zeitschr. f. Physiol. I. 1824, 8. 53 3 CARUS Lehrbuch der Zootomie, 2te 
Aufl. 1. 1834, s. 650; V. SresoLp Lehrb. d. vergl. Anat. I. 8. 281—284. 
