236 



DISCOVERY REPORTS 



vessels at the outside upper corners of the stomach and two lower than these near the 

 lateral nerves. Farther back in the body there are two laterals near the nerve trunks and 

 a dorsal median vessel above the gut. 



Excretory system. The convoluted tubules lie beside the stomach and gut. They ex- 

 tend forwards to just behind the brain. The posterior limit of the tubules was not seen 

 in either series of sections, but two pairs of efferent ducts — the posterior pair almost 

 2 mm. behind the anterior — were observed. The ducts pass over the lateral nerves, then 

 downwards and outwards through the body wall. 



Nervous system. The brain is peculiarly compact (Figs. 11 A, 12). The ganglia are 

 very close together, so that the rhynchocoel and proboscis are much constricted where 

 they pass through the brain. There is little dis- 

 tinction between dorsal and ventral ganglion. The 

 ventral commissure is extraordinarily deep and 

 broad. In the specimen examined the brain was 

 0-4 mm. long and 0-25 mm. thick. The ventral 

 commissure was 0-27 mm. long and 0-125 mm. 

 thick — half the thickness of the brain and nearly 

 three-quarters of the length. The dorsal com- 

 missure was 0-08 mm. long. The lateral nerves 

 leave the brain at right angles to the long axis. 

 They make a sharp turn back to pass laterally 

 down the body inside the longitudinal muscles. 

 A marked swelling of the nerves occurs after 

 they leave the brain and before they turn. 



The cerebral organs are very small. They are sac-like organs lying some distance in 

 front of the brain and are connected with the dorsal ganglion of each side by a stout 

 nerve which penetrates the muscular sheath and reaches the ganglion about one-third 

 of the length of the brain from the anterior end. The cerebral canals open to the exterior 

 near the tip of the snout (Fig. 1 1 A). 



Ommatoplea ophiocephala , Schmarda (1859), * s considered to have been a Eupolia by 

 Burger (1895, p. 27). Schmarda refers the genus Ommatoplea to Ehrenberg and this is 

 synonymous with Eunemertes (Burger, 1895, p. 13). Schmarda 's account of the worms 

 found under stones and in sand in Table Bay, South Africa, corresponds fairly well with 

 the description given above. His specimens were larger. He mentions the length as 

 1 m., the greatest breadth 10 mm., the colour as lemon yellow or golden brown, and 

 the (eight) eyes in two lines on both sides of the head. The "small egg-shaped sub- 

 terminal" mouth is evidently the opening of the rhynchodaeum, and the terminal pore 

 may have been the opening of the head gland. 



In many ways these specimens are similar to Eunemertes antonina, Quatrefages. The 

 peculiarities of the brain which characterize this Mediterranean species, the swelling and 

 course of the lateral nerves, the position and size of the cerebral organs and canals are 

 alike in both. Even the darkly-stained connective tissue of the cavity of the body, re- 



Fig. 12. 

 (Schmarda). 

 the brain. 



Emplectonema ophiocephala 

 Transverse section through 



