374 



backwards ; and also salivary glands. The oesophagus is pro- 

 vided with a lateral dilatation or crop, but continues of almost 

 uniform width to the stomach, which is an elongated muscular 

 sac, like the gizzard of a bird, with its cardiac and pyloric orifices 

 close together at its upper portion. At a short distance from the 

 pylorus there is a triangular glandular body, which Owen con- 

 siders a rudimentary paiicreas, communicating with the intestine ; 

 the intestine, nearly straight, terminates in the funnel, within the 

 influence of the respiratory currents, which also expel the excre- 

 ments. 



The ink-bag is present in the Argonaut, and is situated near 

 the termination of the intestine, into which it opens, — not en- 

 closed within the capsule of the liver. The liver is of large size, 

 extending from the crop to the stomach ; it consists of two lobes, 

 united for a considerable extent along the median line, gradually 

 extending laterally and forwards so as partially to inclose the 

 alimentary canal ; it is simple and undivided, not numerously 

 lobulated as in the Nautilus. 



The branchiae are two in number, each composed of fifteen 

 pairs of lamellae ; they are concealed and protected by the mantle 

 which forms for them a chamber anterior to the other viscera, 

 into which the rectum and generative organs open. Respiration 

 is affected by the alternate dilatation and contraction of this 

 chamber ; the water rushing in by the anterior opening of the 

 mantle during its dilatation, and being expelled through the 

 funnel during its contraction. The aquiferous system opens by 

 two apertures, one on each side, at the posterior and upper angle 

 of the eye, at the bottom of a slight depression ; and communi- 

 cates with a cavity situated at the upper part of the head, and 

 also with the peritoneal and other cavities. 



There is a single ventricle or aortic heart, surrounded by a 

 pericardium in the centre of the cavity of the body. At the 

 base of the branchiae are two sinuses, which have been called by 

 some authors branchial hearts and pulmonary sinuses ; according 

 to Von Siebold (pp. cit. pp. 289, 292,) these have no muscular 

 fibres, but have a glandular aspect, and are in close relation 

 with the urinary organs — they, however, require further in- 

 vestigation. 



The divisions of the vena cava, and other veins enterin^r the 



