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XXIV. On the Structure of the Heart in the Perennibranchiate Batrachia. By Ricuarp 
Owen, Esq., F.Z.S., Assistant Conservator of the Museum of the Royal College of Sur- 
geons in London. 
Communicated April 22, 1834. 
AS the Reptilia form the transition between those classes of Vertebrata that possess 
the highest and lowest degrees of the respiratory function, they differ considerably 
among themselves both in the extent and mode of respiration, and present correspond- 
ing variations in the external form and internal structure of the heart. This part of 
their anatomy has therefore been a subject of peculiar interest, not only from its phy- 
siological relations, but, as Mr. Hunter first observed!, from its varieties of structure 
exhibiting as permanent conditions some of the transitional states which the heart of 
the warm-blooded Vertebrata successively assumes in its progress towards perfection. 
The knowledge of these different structures has, however, been slowly, and much of 
it recently, acquired. Linnzeus attributed to the whole of his class Amphibia a simple 
bipartite heart, as in Fishes, ‘‘Cor uniloculare uniauritum.” But prior to the publi- 
eation of the 12th edition of the ‘Systema Nature’, the more complex structure of the 
Tortoise’s heart had been described by Duverney and Méry in the ‘ Mémoires de l’Aca- 
démie des Sciences’, as well as by Bussiéres in the 27th volume of the ‘ Philosophical 
Transactions’. Hasselquist had also pointed out the superior organization of the heart 
of the Crocodile+. Daudin', therefore, in his systematic work on Reptiles, admits the 
double auricle in the heart of the Chelonia and Sauria, but characterizes the Ophidia, as 
well as Batrachia, as having the simpler bipartite form of the organ ; and this is sanc- 
tioned by Blumenbach as far as regards the Serpents of Germany. Cuvier and Meckel, 
however, more correctly attribute to the Ophidia a heart with two separate auricles ; 
but in their latest writings® they state the single auricle to be common to, and charac- 
teristic of, the Batrachian order of Reptiles. 
Meckel, indeed, after premising that the Batrachia have the simplest form of heart, 
‘which consists uniformly of but one auricle and ventricle, of which the first receives 
the blood by many trunks from the body and lungs at the same time,’’? afterwards 
' On the Blood, p. 135. 2 For the years 1676, 1703. 
3 For the year 1712. p. 172. he figures given by this author appear to me to be more faithful, and from 
the mode of dissection employed more intelligible, than those of Méry. 
‘ Itin. Hgypt. et Palest., p. 293. 5 Hist. Nat. des Reptiles, tom. i. p. 335. 
° Cuvier, Régne Anim., nouy. ed., tom. ii. p. 101.—Meckel, Vergl. Anat., band v. p. 215. 
7“ Die Batrachier haben die einfachste Herzform. Das Herz besteht sehr allgemein nur aus einer Vorkam- 
mer und einer Kammer, von denen die erste das Blut durch mehrere Stiimme aus den K6rper und den Lungen 
zugleich aufnimmt.’’—Loc. cit., p. 215. 
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