ANATOMY OF THE TEREBRATULA. 19 



teste, le liquide globiileux paroissant y etre renferme dans une espece de large canal 

 pratique dans le parenchyme de ces parties." (p. 439.)^ 



It was, probably, owing to the misinterpretation of the remarkable facts which 

 Cuvier had observed, that Meckel, notwithstanding the analogous structures, in the 

 meanwhile pointed out by Jurine in the Argulus, and by Gaspard^ in the Helix 

 pomatia, was led to deny the existence of the apertures of communication observed by 

 Cuvier in the large muscular venae cavse of the Aplysia. In 1832, however, I detected 

 a structure in the venous system in the Nautilus Potnpiliiis, closely analogous to that 

 which Cuvier had pointed out in the Aplysia : but, having traced the continuity of the 

 proper lining tunic of the great muscular vena cava, through the apertures in that coat, 

 with a similar membrane lining the abdominal cavity, I was led. to describe the tunic of 

 the abdominal sinus as the peritoneum. " There are several small intervals left between 

 the muscular fibres and corresponding round apertures in the membrane of the vein 

 and in the peritoneum, so that the latter membrane is continuous with the lining 

 membrane of the vein."^ And, after referring to the analogous structure in the Aplysia, 

 I add that this correspondence leads to the " suspicion that it may be more generally 

 found on a further and more dihgent investigation of the venous system in this remarkable 

 class of animals." 



Ten years later, M. Pouchet,* Professor of Zoology at Rouen, demonstrated in Limace, 

 a structure answerable to that which M, Gaspard had described in Helix: viz., that the 

 blood passed from the arterial capillaries into the visceral cavity, whence it was received by 

 particular orifices into the veins that carried it directly to the pulmonary chamber, rami- 

 fying there like a 'vena portae' before returning to the heart. 



In 1834, the same year in which I edited the figures and descriptions by Hunter of 

 the Circulating System in the Lobster, M. Milne Edwards recorded his examination of 

 the same system in the same species, in the ' Histoire Naturelle des Crustaces,' vol. i, 

 p. 101. He there describes the expanded venous sinuses, as " plutot des lacunes situees 

 entre les divers organes que des canaux a parois bien formees." (Op. cit,, p. 102.) The term 

 ' lacunes' is also adopted for that of ' venous sinuses' by the Editor of the posthumous 

 edition of the 'Lemons d' Anatomic Compare of Cuvier,' t. vi, 1839, pp. 504, 505. 



In 1843, M. Quatrefages^ believed that he had discovered a MoUusk, his Eolidina 

 paradoxum, in which the organs of circulation were reduced to a univentricular heart and 

 a system of arteries. " Le systeme veineux," he writes, " manque entierement. II est en 

 quelque sorte remplace par des lacunes du tissu areolaire." In the same nudibranchiate 



^ Sur VArguIefoliace, in 'Annales du Museum,' torn, vii, p. 431, 1806. 



2 Reeherches sur la Physiologie de I'Escargot des Vignes {Helix pomntia), 'Journal dc Physiol, de 

 Mageudie,' 1822, t. ii, p. 295. 



3 Owen, on the Pearly Nautilus, &c., 4to, 1832, p. 28. 



* Reeherches sur I'Anat. et la Physiol, des Mollusques, 4to ; Rouen, 1841. 

 5 Annales des Sciences Nat., 1843, t. xix, Comptes Rendus, 1843, p. 1124. 



