180 Thirty-fifth Report oi* the State Museum. 



fig. 5). The dorsal margins of the outer palpi are attached to the 

 inner face of the mantle, that of the inner laminae to the foot. The 

 onter and inner palpi of each side of the animal are united along a 

 line designated by dots on fig. 6, PL 13. The outer faces of the 

 laminae are smooth and consist of a thin layer of epithelium ; the 

 inner faces, for two-thirds the length from the posterior portion, are 

 strongly ridged transversely ; the free edges of the palpi being crenu- 

 late. There are about eighteen ridges in the space of five millimetres. 

 The summits of the ridges have comparatively large vibratile cilia (PI. 

 13, fig. 7). At a point two-thirds of the length of the palpi distant 

 from the posterior ends the transverse ridges abruptly terminate, and 

 from that point to the mouth the ridges are irregular and longitudinal, 

 also ciliated. When the animal is living the inner face of the outer 

 palpi and the outer face of the inner palpi are slightly distant from 

 each other. The current of water which contains the minute animal 

 and vegetable substances constituting the food of the Anodonta, is by 

 the cilia of the transverse ridges of the palpi carried toward the 

 mouth, and by the action of the cilia of the longitudinal ridges di- 

 rectly to the mouth, and then by the cilia of the lining membrane of 

 the oral cavity and short oesophagus, to the stomach. 



The Liver. 



(Plates 4, 6.) . 



The liver invests the stomach (PL 6, fig. 1, 1.), and consists of a 

 greenish brown sponge-like mass, formed of caeca or tubes arranged 

 in racemose clusters, and communicating with the stomach by means 

 of minute orifices ; the caeca or tubes (PL 4, figs. 7, 11) are lined with 

 epithelium cells. 



The liver is abundantly supplied with blood and from the blood the 

 caecal tubes extract a fluid which resembles the bile of animals of 

 higher organization, which fluid enters the stomach by means of the 

 orifices previously mentioned, and aids in the process of digestion. 



The Rekal Orgak. 



(Plate 9.) 



The renal organ, or organ of Bo j anus is situated immediately below 

 the pericardium. It is thus called after the name of its discoverer, 

 Bojanus. This name has not been universally adopted and I shall use 

 the term renal organ as being more appropriate. 



The renal organ consists of two symmetrical lateral parts. Each 

 part is separated into two chambers, the upper and the lower. 

 The upper is the smaller and known as the non-glandular or pleural 



