232 



DISCOVERY REPORTS 



for the size of the head. The ventral commissure is wider than the dorsal. The 

 dorsal ganglia divide posteriorly into upper and lower branches. The small upper 

 branches taper away rapidly while the lower become included in the cerebral organs 

 which swell to form substantial lobes lying almost free at their hinder ends in blood 

 sinuses formed from the lateral and median vessels. The ventral ganglia become the 

 lateral nerves beneath the cerebral organs and leave their positions on either side 

 of the rhynchocoel to pass down the body. Neurochord cells were observed in the 

 cellular tissue of the inner face of the ventral ganglia just posterior to the ventral 

 commissure. 



The cephalic slits are apparent very near the tip of the head. They do not extend 

 posteriorly beyond the cerebral canals, which pass in directly opposite the lower cornua 

 of the dorsal ganglia. 



As far as I am able to judge from the incomplete specimen the identification of this 

 worm with C. aerugatus is justified. 



Cerebratulus fuscus, Mcintosh, 1873 (Plate XV, fig. 8; Figs. 9, 10). 



Eighteen specimens were taken during August and September. This species was 

 fairly common in the kelp roots between tide-marks both inside and outside the Bay. 

 The lengths varied between 2-3 and 3-5 cm. with breadths of o-8 and 1-4 mm. Speci- 

 mens with eggs were collected on August 14. 



Form and colour in life. The body is a little flattened from above down. The head is 

 flat, not distinctly marked off from the body, and it tapers to a blunt snout. The cephalic 

 slits are very long and the mouth is 

 small, placed at the end of the head 

 behind the brain. The small eyes vary 

 in number and are deeply embedded. 

 There are usually ten visible on each 

 side ; five together near the tip of the 

 snout, the others in a line farther back. 

 A caudal appendage is present. The 



range of colour is from pale buff to a d 



pink or light red on the back with Fig> 9 . Cerebratulus fuscus, Mcintosh 

 scattered reddish brown splashes preserved specimen, x 4 

 mainly near the middle line and less show the eyespots. 

 definite and paler at the posterior end of the body. The underside is pale flesh colour. 



Form and colour of spirit specimens. An outline sketch of a preserved specimen is 

 shown in Fig. 9A. Neither eyes nor markings are visible. On clearing in anilin oil the 

 eyes can be seen (Fig. 9B). The colour is completely bleached. 



Internal structure. Frontal organs are present. The head glands are fairly well de- 

 veloped. They are more numerous dorsally than ventrally and they can be seen dorsally 

 in transverse sections almost to the posterior end of the brain. They stain deeply with 

 haematoxylin but not so deeply as the subepithelial gland cells. Eosinophile cells are 



A, sketch of the 

 lateral view of the head to 



