6 A. C. OUDEMANS. 
dissection, but can only be satisfactorily studied when cut into 
microscopical slices, it is easily understood that such research 
can only be made by examining a complete series of slices of 
the same animal. This may be performed very easily when 
using the microtome of Caldwell, and the sticking-method of 
Giesbrecht. 
The thickness of the slices varied between 7, and ;i> 
millim. So I obtained series of 
Cephalotrix linearis (Rathke), Oerst., one specimen, 
transversally, the foremost part to the intestine (230 slices). 
Carinella annulata (Mont.), McInt., three specimens 
transversally, of each, the foremost part to the intestine 
(behind the nephridial system), (resp. 730, 800, or 2550 
slices). 
Valencinia Armandi, MclInt., one specimen, trans- 
versally, the foremost part to the intestine (behind the nephri- 
dial system) (880 slices), and the tail. 
Valencinia longirostris, Quatr., one specimen, trans- 
versally, totally (2300 slices) cut up. 
One specimen, partly sagittally partly transversally (1940 
slices). 
One specimen, the head transversally (200 slices), a piece 
of the intestinal region sagittally (138 slices), and the tail 
transversally (130 slices). 
Polia curta, Hubr., one specimen, in toto, transversally 
(1150 slices). 
Lineus sanguineus (Rathke), McInt., one specimen, 
with a large piece of the intestinal region, transversally (735 
slices). 
One specimen, young, zn toto (720 slices), transversally. 
One specimen, young, the head, transversally (150 slices), 
the cesophageal and a piece of the intestinal region sagittally 
(120 slices) and the tail transversally (200 slices). 
One specimen, intestinal region, sagittally (140 slices). 
Lineus gesserensis (O.F.M.) McInt., one specimen, the 
foremost part with a large portion of the intestinal region, 
transversally (1125 slices). 
