DECAPODA. 
157 
branches, running backwards, becoming gradually smaller and ter- 
minating at the anus. The blood which has nourished these various 
organs, and thus become venous, collects from all quarters into two 
large sinuses*, one on each side and above the feet, and formed of 
venous sacs united in a longitudinal series, or like a chain. It is 
thrown into an external vessel — efferent — of the branchiae, where it 
is renewed and becomes arterial ; thence proceeds into an internal 
vessel — afferent ; and finally seeks the heai’t through canals 
— branchlo-cardiac — laid beneath the arch of the flanks. All the 
canals of a side unite in one large trunk, and open into the 
lateral and corresponding part of the heart by a single orifice, the 
folds of which form a double valve that opens to allow the transit of 
the blood from the branchiae to this viscus, but prevents a retrograde 
motion by closing. Examined internally, the heart exhibits numerous 
fasciculi and muscular fibres, variously intercrossed and forming se- 
veral small chambers before the orifices of the arteries. These 
chambers arc so many small auricles, which communicate freely 
with each other when it dilates, but appear to form a similar number 
of little cells for each vessel when it contracts, their capacity being 
proportioned to the quantity of blood in their peculiar vessels. These 
vessels debouche in the interior of the heart by eight openings, the 
two lateral valvular ones above mentioned included. Such, with 
the exception of some modifications f , is the general system of the 
cu’culation in the Decapoda. 
The superior face of the brain;]; is divided into four lobes, each of 
* These learned naturalists compare them to the two lateral hearts of the Cepha- 
lopoda, and the analogy has been admitted by Baron Cuvier in his general report on 
the transactions of the Acad. Roy. des. Sc., for 1827 ; but the idea had been com- 
municated by me to M. Audouin, and was a necessary consequence of my theory 
of the circulation of the blood in the Crustacea, published in a note of my Esqiiisse 
(Tune Distribution Generate dv, Rhjne Animal, 5. As the writers alluded to have 
taken no notice of what I have stated in this particular, both in the pamphlet quoted, 
and in my work on the “ Families of the Animal Kingdom,” I beg leave to produce 
that note. “ I submit the following opinion to the judgment of Zootomists, and of 
M. Cuvier in particular, viz. that in tliose of the Vertebrata possessed of a circula- 
tion, the organ called heart represents, in its functions, a left ventricle, the arterial 
and dorsal trunk of Fishes and of the larvee of the Batrachians ; that one or two 
arteries, which in the Cephalopoda have the form of hearts, replace the right ven- 
tricle. The focus of the circulation, highly concentrated in the first of the Verte- 
brata, thus becomes gradually- weaker, so that finally there is no circulation whatever. 
The dorsal vessel of Insects would then be the mere rudiment of the heart of the 
Mollusca and Crustacea.” I will add, that twenty-five years ago, in my Hist. Nat. 
des Crust, et des Insectes, I rectified the error of Roesel respecting the nervous cord of 
the spinal marrow, which had been taken for a vessel. 
•f* See general observations on the family of the Macroura. 
J These observations are extracted from the Lefons d'Anatomie Cornparce of Baron 
Cuvier. For other details and particular facts, see the Memoir of Messrs. Audouin 
and M, Edwards, loc. cit. 
