REPORT ON SPIRULA. 
21 
lias thick and muscular walls, whilst that on the left is separated from the rest of the 
organ by a distinct constriction, and its walls, like those of the median portion of the 
stomach, are thin and semitransparent. In front of this constriction its surface appears 
marked by numerous transverse striae. 
The thickening of the walls of the cardiac division is almost limited to its left 
(external) side, and arises specially from the strengthening of the muscular envelope of 
this region. The mucous layer of this cardiac sac is thick and spongy throughout. 
The muscular covering of the right (axial) side is not much stronger than that of the 
rest of the stomach. 
The pyloric division has the form of an ovoid spiral sac (PI. VI. fig. 2) united to the 
stomachal cavity by a broad neck. Its internal face is marked by a deep corrugation or 
depression (PL VI. fig. 3, a), which corresponds to a falciform prominence in the interior 
of the sac. The interior of the neck is smooth, but just where it passes into the pyloric 
caecum immense folds of the mucous membrane commence, and become more and more 
strong and permanent, spreading in a slightly curved spiral over the surface of the internal 
sac (PI. VI. fig. 4) and converging on its opposite face. The surface of the folds is 
itself marked by close-set oblique furrows. The junction between the pyloric division of 
the stomach and the intestine is marked by'only a slight fold representing a pyloric 
valve. 
To the right side of the cardiac sac in Spirula peronii is attached an elongated, recurved 
and whitish-looking, body (PI. VI. fig. 3, z), with a glandular appearance, lying in 
the fold of the “ peritoneum,” from which arises the peduncle of the ovary ; in Spirula 
reticulata this body was not seen. 
The liver consists of two compact equal masses, a right and a left, which occupy the 
whole space left free by the otocysts, the salivary glands, and oesophagus, in the anterior 
half of the cavity of the body (PI. IIP, lip.). Each of them is produced into a posterior 
lobe (PI. VI. fig. 1), which with its corresponding lobe fills the pallial sac occupying the 
last chamber of the shell (PI. V. fig. 1, lip'.). 
The two hepatic ducts run from the anterior to the posterior region of the body with 
the oesophagus (PI. III., hpd.), the one passing behind, the other in front of, the left 
division of the stomach (PI. VI. fig. l); they unite and open into the pyloric appendage. 
After having reached the stomach each tube is furnished with a great number of villous 
“pancreatic” caeca (PL VI. figs. 1, 2). The pyloric sac of the stomach and the 
pancreatic appendages of the hepatic tubes are freely surrounded by a thin transparent 
membrane (PL III . ptn.), an invagination of the “peritoneum” or walls of the viscero- 
pericardial cavity into which they thus project. 
The intestine is very short and relatively wide; it arises from the left half of the 
stomachal pouch. It passes downwards and forwards, on the left side of the 
spire of the shell, and gradually narrows; it terminates at the anus, which is placed at 
