EEPOKT OX THE MARSENIAD-dS. 9 



The oesophagus is relatively short and wide, and is frequently somewhat enlarged below 



into a sort of crop. It descends to the right, or to the left, or sometimes directly backwards. 



In some genera (CJielyonotus, Marsenia), the canal is connected before the cardia with a 



saccular proventricuhis, which lies along the right of the anterior side of the foliated 



stomach, and further forward. The oesophagus opens into the lower anterior portion of the 



altogether peculiar foliated stomach. This organ has a cap-like form, due to its more or less 



hollowed-out anterior portion, and is arched posteriorly. The small and flattened cavity 



communicates anteriorly with the oesophagus, and is continued posteriorly to the true 



stomach ; the wall is very thick, and formed of a number (usually 10 to 20) of glandular 



dissepiments, which lie at right angles to the cavity. The whole stomach is more or less 



completely surrounded by a thick glandular layer, which is especially well developed 



inferiorly, frequently almost enveloping the pedal ganglia, and sometimes extending further 



forwards. This glandular mass may perhaps represent the salivary glands, but it does 



not communicate either with the rostral cavity or the bulbus pharyngeus. From the 



posterior side of the foliated stomach a short gut goes obliquely upwards through the thin 



but firm partition between the inferior and superior body-cavities, and through the liver 



to open into the stomach proper on its anterior and lower wall. The true stomach is 



of a roundish shape, has a considerable width, and exhibits, besides the cardiac opening, 



several wide bile-duct apertures. It is continued on without marked boundary into the 



intestine, and is seen (as also the posterior portion of the latter) shining through on the 



posterior surface of the ujjper visceral mass. Elsewhere it is enveloped by the liver. The 



intestine appears at first as the narrowed continuation of the stomach ; it then extends to 



the left, and, just in front of the pericardium, bends with a knee-like curve into the 



anterior stretch, which runs along on the right of the front side of the liver. Finally, 



twisting forwards, it ends in the anal papilla, at the right corner of the branchial cavity. 



The contents of the digestive cavity were for the most part unrecognisable animal 

 remnants (probably mostly of Alcyonidse and Ascidians). In the intestine these appeared 

 usually as oval or short sausage-shaped, white or darkish, firm masses of excrement. 



The liver * exhibits the ordinary structure. It is penetrated by a network of bile-ducts, 

 which are wide terminally, and open by several round apertures into the true stomach. 



The pericardium, the heart, and the vascular system do not seem to differ essentially 

 from those of other Prosobranchiates. 



The kidney is usually comparatively small, and situated on the left ; it occasionally 

 attains a larger size, becoming broadened out posteriorly (Onchidiopsis) ; or it may lie 

 transversely behind the branchia {Marsenina). The structure agrees* with that in other 

 Prosobranchiata. It communicates by a fine pore with the pericardium, and opens by a 

 slit on the left into the branchial cavity. 



1 Cf. Barfurth, Ueber den Bau u. die Thatigkeit der^Gasteropoden-Leber/^rt'Aw/. Mikr. Anat., 1883, Bd. 

 xxii. pp. 473-524, taf. xx. 



(ZOOL. CHALL. EXP. PART XLI. 188G.) Ss 2 



