NEMERTEANS 



23' 



Genus Cerebratulus, Renier 



Cerebratulus aerugatus, Burger, 1892 (Plate XV, fig. 5; Figs. 7, 8). 



The anterior end of a Lineid worm was found in a kelp root torn from the rocks be- 

 tween the whaling stations. The length was 5-5 cm., the breadth of the head about 

 i-omm. A distinct shallow groove was 

 noticed in the mid-dorsal line of the head. 

 The diverticula of the gut were very regularly 

 placed opposite one another. 



Form and colour in life. The body is soft 

 and a little flattened. The head is lance- 

 shaped, flat and broader at the level of the 

 ends of the cephalic slits than the succeeding 

 part of the body. The cephalic slits are very 

 long. There are no eyes. The mouth is 

 small, placed mid-ventrally behind the ends 

 of the cephalic slits. The body is reddish 

 brown towards the anterior end, fading to 

 yellow posteriorly. The greater part of the 

 head is white. A vague red patch is visible 

 dorsally and ventrally where the body colour 

 fades at the back of the head. In spirit the 

 colour is brownish. 



Internal structure. The tip of the snout was unfortunately 

 missed in sectioning so that the frontal organs are not known. 

 The head glands are thin and scattered. They extend back as 

 far as the brain. No trace of eyes could be seen. In the 

 stomach region the epithelium is about as thick as that part 

 of the longitudinal muscles into which the cuticular glands 

 penetrate. The outer longitudinal muscle layer is from three 

 to four times as thick as the circular layer, while the inner 

 longitudinal layer is thinner than the circular. There is no 

 diagonal layer. The circular muscles of the rhynchocoel are 

 about as thick as those of the circular layer of the body 



(Fig- 7)- 



There is a vascular loop in the head. Posterior to the brain 

 the dorsal vessel protrudes into the rhynchocoel and a number 

 of blood spaces of varying size surround the stomach (Fig. 7). 

 The excretory system is not known. 



The relations of the brain and cerebral organs are shown in 

 Fig. 8. The fibrous tissue of the dorsal ganglia is about twice 

 as extensive as that of the ventral and the brain is large 



Fig. y. Cerebratulus aerugatus, Burger. Transverse 

 section through the body to show the relative 

 thickness of the muscle layers. 



Fig. 8. Cerebratulus aerugatus , 

 Burger. Diagram from a 

 graphic reconstruction of the 

 brain and cerebral organs 



