242 



DISCOVERY REPORTS 



rhynchodaeum. The organs are small and do not reach the ganglia, but a stout nerve has 

 been traced to them from the brain. 



A - B 



Fig. 15. Zygonemertes capensis, n.sp. A, transverse section across the head at the level of the ventral com- 

 missure ; B, transverse section across the body at about half its length to show the opening of the genital sacs ; 

 C, transverse section 0-025 mm - from tip of tail. 



In some specimens the protruded proboscis is nearly as long as the body, in others it 

 is about a quarter of the body length. These differences are probably due to different 

 states of contraction and extension of the proboscis and body on fixing. There are thir- 

 teen nerves. That part of the proboscis posterior to the armature 

 is shorter than the anterior part and is inserted in the rhynchocoel 

 at about one-third or half the length of the body. The rhynchocoel 

 extends to the posterior end of the body (Figs. 15 B and C). The 

 armature (Fig. 16) consists of a main stylet on a base of unusual 

 length, and two accessory reservoirs each with two, three or four 

 stylets. Often one of the accessory stylets is incomplete. The base 

 of the main stylet varies between two and a half to five times the 

 length of the stylet. Measurements of three armatures from green 

 and brown forms are given below : 



o-i33 



0-130 



Main stylet (mm.) ... 0-115 ° -I 56 

 Base of stylet (mm.) ... 0-518 0-714 

 Accessory stylet (mm.) 0-164 0-182 



In the uncoloured forms the difference in length between base 

 and main stylet is not so marked : 



Main stylet (mm.) 0-078 0-050 



Base of stylet (mm.) ... 0-117 0-084 



Fig. 16. Zygonemertes 

 capensis, n.sp. Arma- 

 ture of the green form 

 (cleared in anilin oil). 



