NEMERTEANS 



271 



dilated or very capacious and full of nucleated corpuscles. This appears to be a constant 

 character of the species, though it does not always appear in life in the marked form 

 shown in Plate XVI, fig. 23. 



The cerebral organs are very small and far in front 

 of the brain. The relative positions of the brain, cerebral f-jpr 

 organs, eyes and head glands can be seen in the graphic 

 reconstruction (Fig. 47). The anterior caecum has no 

 forward branches and lies far behind the brain. The 

 brain is large, the dorsal ganglia being about equal in 

 size to the ventral and continuing into the lateral nerves 

 down the body. 



I have not been able to identify this form with any 

 known species although it approaches T. belgicae, 

 Burger, 1904a. 



Tetrastemma georgianum, Burger, 1893 (Plate XVI, 

 figs. 2, 13; Fig. 48). 



This species was first noted from King Edward 

 Cove. Two specimens were taken in September and 

 four in October 1925, from kelp roots. A single speci- 

 men occurred at St. WS 65 in Undine Harbour. The 

 smallest worm was 3-5 mm. long, but the usual length 

 was from 10 to 15 mm., breadth 0-7 mm. The original 

 sketch and description were made from six specimens 

 (N 7). In 1929 a single specimen was collected in the Fi 8- 47- Tetrastemma esbenseni, n.sp. 

 , 1 • it- t^j j r> i_ • 1 -j sn j Graphic reconstruction of the head and 



dredge in King bdward Cove which was identified . . c , , , , , 



° anterior end 01 the body, co, cerebral 



later with a larger form described under N 15, no organ;*, anterior eye -hg, head glands, 

 differences being found in sections. The size attained 



may be 25-0 mm. Other captures were made — three specimens at St. 123, one at St. 140 

 and one at St. 51 (identified from sections, N 126). 



Form and colour in life. The head is somewhat round in outline from above, but the 

 snout has a median vertical cleft. The body is broadest at about half its length and is 

 tubular and soft. The colour is brown, brownish red or mauve on the back, much paler 

 beneath. With a low magnification (x 10) the pigment appears granular. On the head 

 the pigment band narrows and becomes defined so that the head appears to be bordered 

 with white. On each side a white tag or strip passes up, while a little farther back the 

 body colour is separated from that of the head by a fine white line which forms a wide 

 V with the apex pointing back. I have never seen the anterior tags joined as a band. 

 Four eyespots are present in two pairs. The first pair is situated at the anterior edge of 

 the head pigment ; the second lies within the white tags. A pair of vertical furrows which 

 may be tinged with red can be seen in the tags. 



Form and colour of preserved specimens. Length 9 and 13 mm., breadth o-8 and 



