THE ANATOMY OF A NEW SPECIES OF BATHYDORIS. 195 



tube with muscular walls lined, as already mentioned, by a thick cuticle. At its lower 

 end it ends in a thin-walled sac, the stomach (st., fig. 5), lying below the liver, and 

 partially imbedded in its substance. The lining of the oesophagus is, throughout its 

 length, thrown into twelve raised longitudinal bands (b.o. , fig. 5) which are covered with 

 minute, blunt, brown cones of various sizes. As shown in fig. 6, the cones are partly 

 imbedded in the cuticle of which they are specially resistent local modifications. The 

 dark tint of the cuticle of the first half of the oesophagus and the extensive crinkling 

 of its walls obscured the presence in it of the longitudinal bands which were only seen 

 after clearing. Eliot, who describes the denticulate bands in the second half of the 

 oesophagus, may have overlooked them in the first half for the same reason. The same 

 writer, in his account of B. hodgsoni, names the two regions of the oesophagus the first 

 and second stomach — names which seem inappropriate for a thickly cuticularised tube 

 which serves merely for the delivery of the food to the sac in which it is actually 

 digested. The denticulate cuticle would, moreover, be quite ineffectual for the purpose 

 of mastication, and probably serves as a protective layer against the coarse diet of mud, 

 sponge, and small shells The thin-walled stomach stands at the junction of oesophagus, 

 intestine {int., fig. 5), and main liver ducts (l.t.) into the expanded ends of which the 

 food enters for some distance, as in Dorids generally. At its junction with the oeso- 

 phagus the stomach has a small pocket (s.r.) like that of the Dorids, which was not seen 

 in any of the other species. Its function is not known, though such inapplicable names 

 as " pancreas " and " gall-bladder" have been applied to it by different authors. 



It may be mentioned that the similar stomach recess in Doris tuberculata secretes 

 a glassy, refringent substance which is also found as a granular deposit on the mucosa 

 of the intestine and on the massed Halichondria spicules passing down that tube. This 

 suggests a protective function for the organ, its secretion acting as a lubricant for the 

 passage of spiculose excrement down the intestine. The liver (I., figs. 2 and 5) is a 

 bulky organ which is not invaded by gonad or kidney, and is unlobed except in so far 

 as the intestine and the lower end of the oesophagus lie in furrows on its surface. The 

 intestine is a rather broad, smooth tube making an arc round the pericardium and end- 

 ing by a sphinctered opening on the anal papilla. 



The alimentary tract contained one large piece of undigested sponge, and sponge 

 spicules were present in all parts of the stomach and intestine. There were also found 

 much mud, bits of old shells, small pebbles, and the spines of Echinids. The animal is 

 therefore probably an omnivorous feeder, though the prevalence of sponge suggests that 

 it has predilections for that group, like the Dorids. 



The salivary glands {s.g., fig. 2) are fiocculent and voluminous, forming a mass on 

 each side pressed against the wall of the oesophagus, and opening by stout ducts on 

 the hinder wall of the buccal cavity. Bergh and Eliot mistook them for the blood 

 glands, but their histological structure puts their salivary nature beyond doubt. 

 Moreover, the true blood glands were found elsewhere. 



