THE "TRITON" TUNICATA. 109 



the posterior end of this the short curved intestine emerges. The stomach 

 lies in the 5th intermuscular space, and the intestine runs backwards till it 

 almost or quite reaches the 7th muscle band, and then turns dorsally and to 

 the right, and finally runs forwards to terminate in the anus placed in the 5th 

 intermuscular space, over the stomach (PL XVIII. fig. 4). According to 

 Keferstein and Ehlers the anus is situated at the posterior part of the 5th in- 

 termuscular space, or upon the sixth muscle band, while according to Grobben 

 it lies in the 6th intermuscular space. Huxley figures it in the fifth inter- 

 muscular space. The epithelium lining the intestine is polygonal in surface 

 view (PL XX. fig. 4) and very distinctly nucleated. In the wall of the stomach 

 the cells are columnar and more darkly coloured. 



Two glandular systems, which seem to be quite distinct, are found in 

 connection with this alimentary canal. First, along the ventral surface of the 

 stomach, especially towards the pyloric end, and more or less scattered over 

 the first portion of the intestine, may be found masses of rather darkly coloured 

 glandular-looking caeca (see PL XX. fig. 1, gT). These branch and apparently 

 anastomose occasionally, forming rude networks, but the branches are short 

 and stout, and the meshes small and irregular. No duct or opening into the 

 alimentary canal was visible. With a higher magnification the cseca present 

 somewhat the appearance shown in Plate XX. fig. 5 — masses of cells rounded 

 or polygonal in outline, but rarely angular, having small indistinct nuclei and 

 granular cell-contents. These clumps of branched cseca have apparently not 

 been noticed previously, as I find nothing in the published descriptions and 

 figures which could represent them. 



The second glandular apparatus is the system of fine clear-walled tubules 

 ramifying over the intestine, which was first pointed out in Doliolum by 

 Huxley,* and has since been more or less completely described by Leuckart, 

 Gegenbaur, Keferstein and Ehlers, and Grobben. It has also been recently 

 investigated by CHANDELONt in Perophora and Salpa, where it has very much 

 the same arrangement as in Doliolum. Chandelon comes to the conclusion 

 that the system can be compared neither with a kidney nor a liver, but 

 that it is probably a digestive gland of some kind. 



In the specimens which I examined this system appeared generally well 

 i developed, although it was sometimes difficult to make out, owing to the 

 opacity of the alimentary canal caused by its food contents. In Plate XX. 

 fig. 1, d indicates the duct of this system, which is a clear- walled, almost 

 transparent vessel, entering the pyloric end of the stomach. From this point 

 it may be traced upwards and backwards (PL XX. fig 1, represents a specimen 



* Phil Trans., 1851. 



t "Recherches sur une annexe de tube digestif des Tuniciers," Bulletins de I'Academie Royale de 

 Belgique, 2 me ser. t. xxxix. No. 6, 1875. 



VOL. XXXII. PART I. T 



