DONDERSIA CALIFORNICA. 157 



bearing portion whicli in turn connects with the stomach-intestine l^y a short 

 oesophagus. 



Dorsal saUvary ghinds are represented l)y a small number of pyriform cells 

 commimicating with the pharynx immediately behind the level of the brain. 

 Slightly more posteriorly there are other similar cells, but they cannot with 

 certainty be differentiated from the anterior pedal gland. The ducts of the 

 ventral salivary glands open close to the mid line on each side of the forward 

 end of the radula (Plate 23, fig. 5). Distally they make their way, as slender 

 tubes, in a lateral direction and then expanding to twice their initial diameter 

 proceed for a short distance posteriorly. To this expanded portion are connected 

 multitudes of pyriform gland cells arranged somewhat intlefinitely into lobules 

 attachetl to the lateral and ventral walls of the jiharynx. In 1). aiundatu Nier- 

 strasz ('02) finds numerous cells situated about the ventral ducts; it is probable 

 that they are the salivary cells whose ductules have been destroyed owing to 

 faulty fixation. 



The radula is comparatively small and the teeth very transparent so that 

 it is somewhat difficult to discover their exact form. Judging from cross sections 

 each tooth consists first of a basal plate (Plate 8, fig. 8), narrow rectangular in 

 form, and without any connection with the plates of neighboring teeth. This 

 basal bar supports what appears to be a triangular median tooth, but high 

 powers resolve this into a pair of elements closely appressed. It thus apjiears 

 that the radula is monoserial, each l)ar l)earing a pair of conical cusps. On the 

 other hand the radula may be considered biserial, the basal bar representing a 

 basement membrane, but against this is the fact that the bars are not united 

 with each other. There are not less than twelve teeth if the radula be con- 

 sidered monoserial. 



Beyond the radula the digestive canal narrows, becomes folded longitudi- 

 nally and opens abruptly into the stomach-intestine that after forming a short 

 dorsal and ventral coecum develops the deep, characteristic lateral pouches with 

 glandular walls. In the mid dorsal line the epithelium is differentiated into a 

 fokl composed of high, richly ciliated cells which laterall.v become reduced in 

 height ;ind gradually shade into the non-ciliated digestive cells. The relations 

 of the gut to the cloacal cavity are indicated (Plate 6, fig. 2). 



The pericardium is spacious and the heart is of more than average size. 

 The blood from the posterior regions of the body pours into its posterior division 

 corresponding to an auricle (Plate 6, fig. 2), thence into a ventricle-like portion 

 and from there is driven into the aorta. This vessel throughout its entire extent 



