192 F. W. GAMBLE, B.SC. 



Claparede suggested, that this species attains a considerable size 

 before the reproductive organs begin to develop. Thus he found 

 individuals 1*5 — 2 mm. long without a trace of gonads, and I have 

 myself observed the same thing. 



The form of the body changes with different states of contraction 

 and expansion. When freely swimming the form is that of (53) 

 pi. xi, fig. 15, the sides flexed ventrally, almost touching one another 

 except in front, where they diverge. The hinder end is produced into 

 a finely-pointed tail. The anterior end is truncate, the angles being 

 frequently more or less produced. It is a most actively sensitive 

 animal, especially during creeping movements, when the " head " 

 is converted into a funnel-shaped structure which explores the 

 surroundings. 



The general colour varies from greenish-brown to a warm chestnut- 

 brown, which is the usual tint. The anterior margin is paler than the 

 rest. The brown pigment is deposited in the cell of a "symbiotic 

 alga," the nature of which has not been thoroughly investigated. 

 Transverse, narrow white bars, 1 — 2 in number (v. Graff has observed 

 three, and Claparede [35, pi. vi, fig. 2] figures four such bands), are 

 present in large individuals (1*75 mm. and upwards). They are the 

 expression of a large number of very small irregular granules, insoluble 

 in acids (v. Graff). Claparede has suggested that these bars may be 

 a " caractere senile." This view is supported by v. Graff, since he 

 finds that the bars become more and more distinct with the increased 

 size and age of the animal. The epidermis contains ftagella, rhabdites, 

 and pigment. The latter forms elongate masses of rod-like granules. 

 The mouth, which is ventral and subcentral, leads into a very short 

 pharynx. The eyes are constantly present in this species. They are 

 red pigmented bodies, and occur right and left of the otolith. 

 Poison-organs (" Gift-Organe ") have been discovered by v. Graff (44) 

 in this and other species of Convoluta (C. grcenlandica, cinerea, flavi- 

 bacillum, bimaculata) . They consist in C. paradoxa of a pair of 

 pyriform, transparent, muscular vesicles, provided with hollow 

 chitinous tips, and are placed at the margin of the body in such 

 a way that when this is flexed ventrally the tips are directed towards 

 the mouth. The contents consist of small refractive granules. At 

 each contraction of the muscular wall the tip is moved forwards, 



