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THE VOYAGE OF H.M'.S. CHALLENGER 
those of the last described species ; the thickness of the walls of the stomach is as much 
as 5 mm. ; the cuticle and the thicker portions of the stomach as above, but less marked. 
The third, lamellated stomach, does not differ at all from that of the last species ; it is 
in the same way radially pigmented, oval, and depressed in form ; the greatest diameter 
12 mm., the less 9 mm., the height only 4 5 mm. ; the band mentioned above as lying 
between the second and third stomachs exists here also ; the height of the leaves 
reaching about 3 '5 mm. ; their structure is precisely similar. Two of the folds of the 
third stomach are continued about 9 mm. into the intestine and then unite, the end hanging 
loose about 1 mm. from the wall ; in this region of the intestine there is, moreover, 
a zone of short longitudinal folds. The intestine has a length of 15 cm. and a diameter 
of 2-2 ’5 mm. — The cavity of the alimentary tract was filled with a dirty yellowish-white 
mass, mainly consisting of littoral Algse, calcareous matter, and Foraminifera ; there were 
also pieces of the radula that had been torn off, even portions of teeth-series, often with 
as many as eight to twelve teeth. 1 
The most anterior of the three greenish-yellowish-grey liver masses measured 22 mm. 
in length by 19 mm. in breadth and 12 mm. in height ; on its right margin were two 
deep obliquely running furrows which united anteriorly, and between them a shorter one ; 
on the left margin was a single deep furrow. The lower liver was 22 mm. long by 8 mm. 
broad and 7 mm. thick, divided into four separate lobes by deep furrows. The hinder liver 
concavo-convex, 23 mm. long, 18 mm. broad, and 6 mm. thick, divided into six lobes 
by two deep furrows on the left and three on the right. The hepatic ducts and their 
apertures as in the former species. 
The milk-white pericardium is precisely similar to that of the former species, the 
hinder portion imbedded in the lateral parts of the back ; the anterior portion is freer 
and attached by short bands to the back and the right lateral wall of the foot. The 
pericardium is compressed, of oval contour, 24 mm. long by 14 mm. broad; the anterior 
portion occupying the first 17 mm. of its length, is thin -walled, and permits the heart 
to be seen within ; the posterior portion shorter, and thicker behind, joins the wall of the 
lung. The heart is like that of the last species ; the length of the contracted ventricle 
was 6 ‘5 mm., the breadth (from above downwards) of the atrium is 14 mm. The aorta 
extends to the anterior end of the upper liver, between it and the intestine, where it 
gives off the strong gastro-hepatic artery upwards, and then, as usual, is continued 
forwards and backwards ; branches of the anterior oesophageal artery supply the salivary 
glands. 
The cavity of the lung is pretty wide, about 13 '5 mm. long by 12 mm. in height and 
8 mm. in breadth ; the inner wall is thin but tough ; in front it joins the hinder wall of 
the pericardium; the inner side, as well as the neighbouring portion of the lower wall of 
1 Semper ( loc . cit., Ergiinzungsheft, p. 30) says that the Onchidia do not feed upon plants or animals, hut take in 
only sand and mud. In nineteen species which he examined, Semper found “nothing hut sand and mud.” 
