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XVIII. On the Anatomy of the Brachiopoda of Cuvier, and more especially of the Genera 
Terebratula and Orbicula. By Ricuarp Owen, Esq., F.Z.S., Assistant Conservator 
of the Museum of the Royal College of Surgeons in London. 
Communicated November 26, 1833. 
IT is to Cuvier that we are indebted for the knowledge of that interesting form of the 
respiratory organ of the Bivalve Mollusks, by which the mantle, in addition to its se- 
creting the shelly defence of the viscera, and constituting their immediate covering, is 
made subservient also to the renovation of the circulating fluids. The dissection of 
Lingula anatina, Brug., which first brought to light this structure, is among the early 
labours of that great anatomist, and forms the subject of his first paper in the ‘ Annales 
du Muséum.’ He observed in Lingula that in the situation occupied by the branchie in 
ordinary Bivalves, there were instead two fringed and spirally disposed arms, and that 
the branchie themselves were arranged in oblique parallel lines along the internal sur- 
face of both lobes of the mantle; that the lobes of the mantle were further charac- 
terized by large vessels returning the blood from the respiratory organs; and tha! 
these vessels (the branchial veins) terminated in two systemic hearts, which were 
symmetrically disposed, thus forming a new type of circulation, corresponding to the 
modification of the respiratory system. 
For the Mollusks possessing these important modifications of structure, Cuvier 
founded a distinct class, which, according to his system of orismology for that di- 
vision of the animal kingdom, he denominated Brachiopoda, considering the fringed 
arms as being in place of the foot in the Cockle, Muscle, &c. 
From the analogy of Terebratula to Lingula in its pedicellate mode of attachment to 
foreign substances, and from such notices of the construction of the soft parts as he 
had then met with, he concluded that its organs of respiration were similarly situated, 
and that what had been taken for branchie by Lamanon!' and Walsh®, were in fact the 
analogues of the fringed arms of Lingula. 
It is remarkable that Cuvier in no part of his Memoir, nor in either of the 
editions of the ‘ Régne Animal,’ should allude to the concise description which Pallas 
has given of the animal of Terebratula in the ‘ Miscellanea Zoologica’’. Under the old 
name of Anomia, which, since the Linnean character is applicable only to the modern 
Terebratule, ought to have been retained for them, Pallas notices the limited situation 
of the viscera. He describes the arms with his usual minuteness and accuracy, but 
considers them as branchie, comparing them to those of a fish (piscium branchiis 
' Voyage de la Pérouse, p. 146. ® Naturforsch., tom. iii. p. 88. ’ P. 182. (Anomiarum Biga.) 
