NEMERTEANS 285 



is composed of an inner longitudinal layer definitely divided into bundles and an outer 

 thick layer composed of circular fibres with some longitudinal fibres among them. 

 Before the brain the muscle layers are reversed, i.e. the inner layer is circular and the 

 outer longitudinal. The proboscis is missing. 



There is no oesophagus. The branches of the gut reach forward beside the brain 



posteriorly. 



The lateral nerves are pressed against the ventral body wall (Fig. 62 B) and contain an 



evident dorsal strand. 



The specimen was a female with eggs developing singly close beside the larval 



nerves. 



That the animal belongs to the genus Nectonemertes is certain from its form, the 

 muscles of the rhynchocoel wall and the position of the lateral nerve cords. I have 

 separated it from Brinkmann's species— primitiva and minima— on the ground of its 

 form and the size of the rhynchocoel and brain. 



Genus Pelagonemertes 



Pelagonemertes rollestoni, Moseley, 1875 (Fig. 63). 

 The following captures were made of this species : 



A specimen from the large haul at St. 107 was sketched directly after capture. An out- 

 line drawing of this sketch is given in Fig. 63 to which the imagination can readily add 

 the transparency of the body, the opacity of the brain, lateral nerves, gonads, proboscis 

 and its sheath, and the startlingly vivid colouring of yellow on red of the branches of the 

 gut. This specimen measured in life 45 mm., and was 23 mm. broad. Another was 

 21 and 12 mm. 



After fixation the gut branches appear considerably thicker than they are in life. The 



