CEPHALOPODA. 



533 



found below the cartilaginous cranium, situ- 

 ated in the hepatic cavity, on either side of 

 the oesophagus. A single excretory duct is 

 continued from each gland, and the two unite 

 and form one, as they are passing through the 

 cranium. The common duct penetrates the 

 lower or central surface of the buccal mass, 

 and is continued along the concavity of the 

 lower mandible, through the tongue to the 

 lower part of the spiny plate, where it termin- 

 ates. In the Octopus these glands are veiy 

 large, and have a smooth surface (q,fg- 233) ; 

 but in many Cephalopods, as in Ocythoe, 

 Sepiola, and Rossia, they are relatively smaller, 

 and have a granular surface. It is in the genus 

 Loligopsis alone that these glands have hither- 

 to been found wanting. 



With respect to the ultimate structure of the 

 salivary glands of the Cephalopoda, Miiller* 

 observes that they are not composed of solid 

 acini or granules, but of hollow canals or cells. 



Before the description of the abdominal 

 viscera is proceeded with, it is necessary to 

 make a few observations on their position and 

 connections. 



In the ventricose and short-bodied species 

 of Cephalopoda the mantle-sac is almost wholly 

 filled with the viscera, but in those of an elon- 

 gated form they are more or less confined to 

 the lower part of the sac, and a vacant space 

 intervenes between the visceral mass and the 

 opening of the mantle, which is traversed by 

 the respiratory currents : the part of the mantle 

 unoccupied by the viscera is most remarkable 

 for its extent in the genus Loligopsis (Jig- 223.) 



If the mantle of the common Octopus or 

 Poulp be laid open longitudinally, and a little 

 to one side of the mesial line, a cavity will be 

 exposed, separated by the longitudinal muscular 

 septum (c,jig. 216) from the corresponding one 

 of the opposite side ; in these two cavities are 

 contained the branchiae (r,Jig. 216), the termi- 

 nations of the oviducts (p J, and the pericardial 

 apertures (q). Below and behind the branchial 

 cavities, the peritoneum is seen enveloping the 

 rest of the viscera ; but this great serous sac is 

 subdivided into many compartments. If the 

 point of the scissors be inserted into the project- 

 ing orifice internal to the root of the gill (i,fg. 

 226), and the cavity of which it is the outlet be 

 laid open, the branchial ventricle, the branchial 

 division of the vena cava, and its appended 

 follicles will be exposed ; this cavity is sepa- 

 rated from a corresponding one on the opposite 

 side by the systemic heart and the great vessels, 

 which are contained in a distinct serous com- 

 partment. In the Nautilus the two lateral and 

 the middle cavities form one large pericardiuc 

 chamber, appropriated to the heart and great 

 vessels, and the venous appendages. 



Behind these cavities, the peritoneum is 

 disposed so as to form several compartments : 

 one, which commences at the cranial cartilage, 

 extends downwards as far as the middle of the 

 branchiae, and contains the oesophagus, the 

 inferior salivary glands, the crop, and anterior 

 aorta : in front of this, but commencing a little 



' De structura glandularum penitiori, fol. p. 54. 



lower down, is a second, which includes the 

 liver and ink-bag. These two cavities are sur- 

 rounded by a common muscular tunic, of 

 which we have already spoken, and the lower 

 part, which resembles a diaphragm, is per- 

 forated by the gullet, the aorta, and the two 

 biliary ducts, each of which has a distinct 

 aperture. The receptacle which contains the 

 gizzard is situated immediately beneath the 

 oesophageal sac ; that in which the spiral py- 

 loric appendage is lodged lies immediately 

 behind the left compartment of the pericar- 

 dium. The intestine is principally contained 

 in a serous cavity behind the right division of 

 the pericardium ; and the bottom of the sac is 

 occupied by the cavity containing the organs 

 of generation. 



The digestive organs in the Tetrabranchiate 

 Cephalopods would appear to differ in a less 

 degree than other parts of their organization from 

 the structures observable in the higher order : 

 in the Nautilus they present the following con- 

 formation. 



The pharynx (f, Jig. 217) or commence- 



Fig. 219. 



Digestive Organs, Nautilus Pompilius. 



ment of the gullet, has numerous longitudinal 

 rugae internally, and is evidently capable of con- 

 siderable dilatation. The oesophagus, after 

 having passed beneath the brain, or commissure 

 of the optic ganglions, dilate into a capacious 

 pouch or crop (k,fg. 219) of a pyriform shape, 

 two inches and three lines in length, and an 

 inch in diameter at the broadest part. From 

 the bottom of this crop is continued a contracted 

 canal (/, fig. 219,) of about three lines in diame- 

 ter, and half an inch in length, which enters the 



