I04 HAROLD HEATH. 



more or less distended with blood in a living condition. It is 

 probable also that they may be extended into the neighborhood 

 of the external opening or even protruded through it. 



A problematic organ, which appears to be a kidney, is situated 

 beneath the stomach anterior to the intestine (Fig. i, k, PI. I.). In 

 this region the body wall is provided with a considerable number 

 of outpouchings of varying size, though usually comparatively 

 short, each of which is invested with a definite cuticular layer. 

 In life all of these are probably filled with blood and are lined 

 with a few connective tissue and muscle fibers some of which may 

 span the cavity. With the exception of a few of the anterior 

 projections the walls are provided internally with a very consid- 

 erable number of relatively slender finger-shaped processes re- 

 sembling those on the inner wall of certain prosobranch kidneys. 

 They differ, however, in being invaginations of the body wall 

 and are lined with a continuation of the cuticular layer covering 

 the body generally. The cells of these minor processes are of 

 moderate size, more or less cubical, though they often become 

 flattened near the tip of the organ, and under high magnification 

 have been seen in several instances to connect with a central 

 lumen by means of delicate pores. Judging from these appear- 

 ances the cells of each of these slender processes extract from 

 the surrounding plasma waste materials, and pass them into the 

 contained lumen from whence they make their way to the exterior. 



While the ganglia are readily located the nerves are not sharply 

 differentiated from the muscle fibers through which they pass and 

 accordingly have been traced in a few cases only. The cerebral 

 ganglia, united by a relatively long commissure, are situated in 

 front of the pharynx and beneath the forward end of the stomach 

 (Fig. I, PI. I.). Two connectives lead backward at the sides of 

 the pharynx to the pleuro-pedal ganglionic masses placed about 

 opposite the level of the posterior border of the proboscis. These 

 last named ganglia are indistinguishably fused though they are 

 distinctly paired and originate a very few small nerves that have 

 been followed for a short distance only. One large branch on 

 each side, arising from the anterior half of the nerve mass, passes 

 dorsally and laterally and breaks up into three divisions. The 

 first passes up into the large fold or pseudo-pallium close to the 



