276 



DISCOVERY REPORTS 



The proboscis is stout. I could not make out more than nine nerves in one of my 

 series of sections, but there were ten in another. The arma- 

 ture consists of a main stylet with two reservoirs each with 

 three stylets. 



The brain is large, the dorsal ganglia being somewhat 

 smaller than the ventral. There is no dorsal strand in the 

 lateral nerves. The cerebral organs are small. They open 

 laterally and only just reach the brain (Fig. 51). 



Two small specimens from St. 42 were examined among 

 the preserved material. One was sectioned and proved to 

 be a female with large eggs. In all characters this specimen 

 agreed with the above description. 



Tetrastemma maivikenensis, n.sp. (Plate XVI, fig. 10). 



Only the external characters of a single specimen (N 19) 

 of this worm are known, and it bears a resemblance (except 

 in size) to T. vermiculus, Quatrefages. The length in life 

 was 40 mm., the breadth 075 mm. The body was soft and 

 round, tapering to the tail. There were two pairs of eyes 

 and the brain could be seen as a bilobed pinkish mass 

 through the body wall. The colour was pale green except 

 at the head which was yellowish. The distinctive marking Fig. 51. Tetrastemma hngistria- 

 consisted of a streak of brown pigment between the eyes of *». n - s P- Gra P hic ^construe- 



tion of the head and section 

 each Side. across the body to show the 



It takes its name from Maiviken, South Georgia, where extreme development of the 

 the specimen was found (St. MS 70). epithelium. 



Tetrastemma stanleyi, n.sp. (Plate XVI, fig. 12). 



Three specimens of this form were collected in Port Stanley harbour under stones at 

 low tide on April 29, 1926 (N 21). The lengths ranged about 40-0 mm., the breadths 



1-2 mm. 



The body is round in section, the head slightly constricted from it, bluntly pointed 

 and somewhat flattened. The tail tapers but ends acutely. There are from one to four 

 eyespots in each group of the two pairs. The general colour effect is reddish brown near 

 the head, paler towards the tail. One animal was olive green. The tip of the snout is 

 conspicuously dark brown. This pigment is continued as a median line to the level of the 

 posterior eyes between which it broadens and terminates . In spirit the colour is bleached . 

 One specimen was of a dull bluish grey colour, evidently caused by the contents of the 

 gut. No eyes could be seen even when cleared. 



Anatomy. The head glands form a compact layer dorsal to the rhynchodaeum and 

 disappear before the brain. 



The epithelium is not very thick but it is equal to the three other body layers. Of 



