Dr. AV. C. M'lntosh on Pelonaia corrugata. 417 



lium-cclls (fig. 10), tipped with a vigorous array of cilia, which 

 arc shorter than those in the fenestrse of the branchial mem- 

 brane. 



The mouth, opening freely at the bottom of the branchial sac, 

 leads into a muscular oesophagus, which is readily distinguished 

 from the intestine by its emptiness. It is marked externally by 

 longitudinal strise in its ordinary state, and is lined with a very 

 closely set layer of cylindrical epithelium richly ciliated on the 

 inner surface. Some of the separated cells are represented in 

 fig. 11. When viewed under pressure, the membrane has often 

 a minutely cellular appearance, the ends of the cells only being 

 visible. The equally muscular stomach is of a dull orange hue, 

 and is marked by longitudinal rugse which have a somewhat 

 regular arrangement. The colour is due to the presence of the 

 liver-cells (figs. 12 & 13), which form dense yellowish masses 

 arranged in a longitudinal manner. Numerous branching bile- 

 ducts were .also apparent, many of them having csecal extremi- 

 ties. Portions of these are seen in fig. 14 ; and they appeared 

 to be lined with epithelium. The inner surface of the stomach, 

 again, is furnished with a curiously folded arrangement of 

 glandular membrane (fig. 15), with its inner surface richly 

 ciliated. These folds are composed of cylindrical ciliated, and 

 rounded granular cells (fig. 16). The addition of a little sul- 

 phuric ether to a slide from the stomach brought out at some 

 parts a beautiful series of fusiform nucleated cells or cell-fibres 

 (fig. 17); but their exact anatomical relations could not be made 

 out. The yellowish colour of the stomach is traced to the 

 pylorus, after which the alimentary canal [h, fig. 2) becomes less 

 muscular, and, in the present instance, is loaded with muddy 

 debris. The inner surface of the intestine is covered with large 

 rounded glands having fatty globules in their iiiteriorj which arc 

 shown under pressure in fig. 18. Numerous Diatomacece oc- 

 curred amongst the muddy debris in the intestine. The gut 

 terminated superiorly at the anal opening. The foregoing 

 organs are retained in situ by delicate membranous bands. 



Lying to the outer side of the branchial membrane in the 

 larger specimen were two rows of bodies like ova {d, d', fig. 8), 

 which proceeded from the bulbous portion for some distance 

 along the stalk. They had the usual structure, viz. granular 

 contents, large nucleus, and nucleolus, as shown in fig. 19. The 

 ova varied in size from -j-l^o to t,V i^^ch or more. 



The inner surface of the bulbous portion had numerous pro- 

 jecting and somewhat pcdiculated bulljr, indicated at o, fig. 2, 

 which, in the larger specimen, were marked externally (within 

 the test) by one bulla, and in the smaller by two. These organs 

 are evidently glandular j and a portion of one is shown, x 350 



