W. B. Coe — Anatomy of Cerehratulus lacteus. 497 



the lateral vessels and the nephridia in Carinoma^ and Oudemans (9) 

 likewise in Garinella. Burger (3) has carefully studied the nephrid- 

 ial system in some of the sqaall species of the Enopla by placing the 

 living animal in a dilute solution of methylene-blue for a few minutes 

 and then compressing it under a cover-glass. By this method he has 

 been able to demonstrate that the vessels of the blood-vascular system 

 stand in very close relation with the excretory canals, but there is no 

 direct communication between the two systems in the Enopla. The 

 canals of the nephridial apparatus are clothed with a ciliated epithe- 

 lium and end in blind sacs ("Kolbchen ") which are also clothed with 

 a simple ciliated epithelium. Swinging in the lumen of each blind 

 sac is a tuft of long cilia (" Wimperflamme"). 



In C. Leydii, a species resembling C. lacteus in many respects, the 

 cephalic lacunae are quite like those in the latter species, but instead 

 of the many small vessels with muscular walls in the oesophagal 

 region, as is the case in C. lacteus, we find the lateral lacunae (Plate 

 XV, fig. 13, Iv) to continue without change of character through the 

 entire oesophagal region, back of which they bend downward to form 

 the lateral vessels beneath the intestine. They do not acquire muscular 

 walls until far back in the oesophagal region. The oesophagus is sur- 

 rounded by large, anastomosing lacunae {ol) instead of small, contrac- 

 tile vessels. The nephridial system occurs in a similar part of the 

 body, but it consists of a pair of longitudinal canals (Plate XIII, fig. 

 10, u) with few branches, lying so closely pressed against the walls of 

 the lateral lacunae {II) as to be partly covered by them. There is a 

 single efferent duct near the posterior end of each canal. 



In C. luridus the large lateral lacunae (Plate XIII, fig. 7, II) in the 

 anterior oesophagal region are covered on their outer borders with a 

 mass of convoluted nephridial tubules {u). But one pair of efferent 

 ducts was seen. 



The nephridial system commences in Lineus socialis (Plate XV, 

 fig. 9) just back of the side-organs. From this point the nephridial 

 canals follow the lateral lacunae far back into the oesophagal region, 

 giving off on the Avay numerous efferent ducts (Plate XIII, fig. 6, ue) 

 which are, for the most part, paired. The number of such ducts 

 seems to vary in different specimens. Oudemans (9) has shown that 

 the number of efferent ducts, in some species, increases with age. 

 Throughout its course the nephridial canal lies closely pressed against 

 the wall of the lateral lacuna which lies near the proboscis-sheath. 



In L. hicolor the oesophagal region is very short, and, although the 

 nephridia commence just back of the mouth, the efferent ducts are 



