426 " THETIS " SCIENTIFIC RESULTS. 



gus, the latter enters it on the axial side of the coil, whence it takes 

 an irregularly spiral course from left to right and anteriorly, and 

 part of the spiral is buried in the digestive gland. The spiral course 

 ends on the axial side on a level with the posterior end of the 

 nephridium. Only very little more than that portion of the 

 spiral lying between the hepato-pancreatic ducts is stomach, the 

 rest is intestine. The wall of the former is thrown into narrow 

 lamellae and bears two rows of hard nodules along the deeper 

 side ; the wall of the latter is thrown into lamellae so broad and 

 numerous as to almost fill its lumen. 



The intestine (int.) passes forward along the axis through the 

 nephi^idium to the rectum {rect.), which extends from the posterior 

 end of the mantle cavity forward to the level of the anterior end of 

 the ctenidium. The lumen of the intestine is only slightly 

 smaller than that of the stomach, whilst that of the rectum is a 

 good deal larger. 



A small portion of the cesophageal gland or Leihliris gland was 

 found ; this was dark sage-green in colour and ribbon-shaped. 

 It lay above the left half of the oesophageal loop, and the main 

 branch of the aorta-cephalica, extending from the anterior limit 

 of investigation to about the middle of the proboscis-sac. The 

 anterior end and its connection with the oesophagus were lost in 

 the general decay in this region. 



The hepato-pancreas (hep.) is a large brown gland occupying the 

 greater part of the visceral coil ; it is bounded anteriorly by the 

 nephridium and pericardium, and posteriorly is overlaid by the 

 gonad. The hepato-pancreatic ducts are two in number ; the 

 first (hep. du.') opens into the stomach just beyond its junction 

 with the oesophagus, and it evidently bears the secretion of the 

 posterior poi'tion of the gland. The second (hep. du.") opens half 

 way down the first turn of the spiral ; this carries the secretion 

 from the anterior portion of the gland. 



The salivary glands were not found. 



3. The Nephridium. 

 (PI. xli., fig. 1, and PL xxxix., figs. 1 and 3.) 



The neph'ridimn (neph.) is very large, its shape is somewhat 

 that of a bean, the convex side corresponding to the axis of the 

 coil. The left wall, which separates this organ from the pericar- 

 dium, is thick and non-glandular, except that portion which 

 contains the pericardial gland. The right wall bears the "glandu- 

 lar mass " of the organ. This glandular mass is in the form of 

 closely packed lamelhe ; these are of a dark brown colour, broad 

 and short, but thin. They are arranged somewhat in transverse 

 series between the branches of the nephridial veins; the individual 

 lamelhe running, for the most part, in a direction parallel to the long 



