8 PERCY SLADEN TEUST EXPEDITION. 



in spirit is a very pale yellowish white. The head is not marked off from the body, and 

 the hind end is pointed ; a caudicle may have been present. 



The epithelium (PL 2. fig. 15), which is high and packed with large unicellular 

 glands, rests upon a thin basement-membrane. Beneath this there is a delicate cutis 

 containing a few small gland-cells and some muscle- fibres. This cutis is considerably 

 thinner than either the epithelium or the well-marked gelatinous layer on which it 

 rests. The inner longitudinal muscle-layer is well developed, and has embedded in it 

 the oesophageal lacunae, which are consequently separated from the alimentary canal by 

 muscle-fibres. 



The vascular system shows a cephalic loop. Large oval corpuscles are a characteristic 

 feature. The dorsal blood-vessel leaves the proboscis-sheath at the hind end of the 

 excretory system. The proboscis has three layers of muscles, and muscle-crosses are 

 present. 



The excretory system is small. It is situated in the mouth-region and barely extends 

 beyond it. One pair of ducts is present, opening laterally just over the nerve-cords. 



The dorsal lobe of the dorsal ganglion of the brain is well marked. The head-slits 

 reach about halfway to the middle line and are not prolonged behind the brain. 



A frontal organ is not present. Eyes are probably represented by a few small 

 structures near the tip of the snout, but the state of preservation does not allow us to be 

 positive on this point. 



12. Lineus hancoeki, sp. n. (Plate 1. figs. 6 a, 6i.) 



Locality. Cargados Carajos, from the reef. 



A single specimen, somewhat fragmentary. The colour when preserved in spirit is a 

 pale yellow-green. The head is markedly spatulate and the mouth very large and open. 

 The general shape is much flattened, but there are no indications of side folds. 



The epithelium contains numerous highly refractive unicellular glands and rests 

 upon a thick basement-membrane. The cutis is very poorly developed and is not so thick 

 as the epithelium; it contains a few circular and longitudinal muscle-fibrils and a 

 sprinkling of small glands which abut directly upon the outer muscular layer. There is 

 no gelatinous layer. 



A well-marked cephalic vascular loop is present. 



There is no proboscis. 



The excretory system starts shortly behind the posterior end of the mouth. Its range 

 is only 2 mm. and the tubules are not found either dorsal or ventral to the nerve- 

 cord, but are collected at the edge of the stomach. Careful search did not reveal any 

 ducts. 



In the brain the dorsal lobe of the dorsal ganglion is well marked, otherwise the brain 

 presents no features of special interest. 



The head-slits are deep, reaching nearly to the brain, and are prolonged beyond the 

 cerebral organs. 



A single frontal organ and numerous small eyes are present. 



