74 PROFESSOR 0. BiJTSCHLI. 



the shape of a test-tube, becoming much narrower pos- 

 teriorly. The author is unable to confirm Clark's statement 

 that the hinder portion terminates in a delicate prolonga- 

 tion. The length of the broad tube is 0*027 mm., and it 

 consists of a perfectly transparent firm mass, of a chitinous 

 nature to all appearance, although no micro-chemical tests 

 were applied to determine its constitution. In no case was 

 the material of a viscid consistency, as stated by Clark. The 

 organism itself occupies only a comparatively small (4) part 

 of the tube, within which it is very moveable. It can 

 stretch itself so far out that nearly the whole of the collar 

 is extruded, or it can very rapidly retract itself to the hinder 

 end of the tube. It is not known what causes these rapid 

 movements of retraction, but in one case a delicate thread 

 seemed to run from the posterior end of the body to the side 

 wall of the tube. The co-operation of the flagellum in this 

 action seems very doubtful. The relations of the flagellum 

 and collar are seen in fig. 8. The flagellum is so delicate as 

 to be scarcely visible. The ingestion of food has not been 

 observed. The nucleus is placed anteriorly, and is made 

 much more visible by the use of acetic acid. A contractile 

 vacuole of considerable size is found in the hinder third of 

 the body. The rate of contraction is slow, and the re-forma- 

 tion is brought about by the flowing together of several 

 small vacuoles, which appear either shortly before or during 

 the systole of the previous vacuole. Once it was found that 

 after the vacuole had contracted and re-formed for some time 

 in one place, it began instead on the opposite side of the 

 body ; this phenomenon probably gave rise to Clark's state- 

 ment that there were two contractile vacuoles as in Codosiga 

 hotrytis. 



Salpingoeca amphoridium, Clark (?), (op. cit., p. 203, 

 pi. vi, figs. 37, 37 d). 



This species has been found only on a single occasion 

 by the author ; it agrees fairly with Clark's description. 

 The appearance of the case is characteristically flask-like 

 (Plate vi, fig. 9) ; in the form described by Clark the fixed 

 end was rounded or somewhat pointed, whilst in this it is 

 broadly flattened; in both cases the organism almost en- 

 tirely fills the case, which thus appears to be a cast of the 

 animal. The collar and flagellum are seen with difficulty. 

 Numerous vacuoles are found within the body, but only one 

 of these is contractile, whereas in Clark's Salpmgceca amph o 

 ridium there were two large contractile vacuoles and three 

 smaller ones. Food vacuoles are seen passing backwards 



