PLYMOUTH XEMEKTEANS. 419 



Genus Cerebratulus. 

 Body usually long and ribbon-like, much flattened, with very thin 

 lateral margins ; well adapted for swimming. Head pointed, lancet- 

 like. Eyes are usually absent. Mouth mostly a long slit. 



1. Cerebratulus fuscus {^fdntush). (Mcintosh. Monogr. PL YI, 

 Fig. 3.) 



Locality : In dredgings from Asia Shoal, Queen's and New Grounds, 

 Millbay Channel, and once from Mewstone Ledge. 



General colour usually pale yellow, only pigmented on the head ; 

 sometimes, however, especially in bigger worms, a brown pigment was 

 distributed all over the dorsum. Brain transparent. No eyes. Head 

 spathulate, not separated from the body. 



Geographical distribution : Sweden, Great Britain, France, Portugal, 

 Mediterranean. 



2. Cerebratulus roseus (Chiaje). (Burger. Monogr. Taf. YL, 

 Fig. 12. 



Locality : Specimens were collected from the Breakwater, May, 1910 ; 

 from Salcombe (Millbay) by Mr. Potts, in 1908 ; from the sand under 

 Batten Castle, May, 1902 ; each time one complete specimen. A fourth 

 specimen, collected from the Breakwater, was found in a tube of pre- 

 served specimens with Micrura aurantiaca. 



The colour of the only living specimen I have seen was a dirty flesh 

 colour; this individual was a female, which whilst being brought in 

 broke into several pieces ; however, no parts, not even the appendix, 

 had been lost. The uncoloured margins were very conspicuous. The 

 centre of the body probably took its darker colour from the eggs, which 

 had an orange-brown tint and were partly deposited through the genital 

 pores, situated in two rows on the dorsum. The mouth is large ; the 

 cephalic slits even reach the region of the mouth. The preserved 

 specimens show the bright yellowish tint characteristic of Cerehratulus 

 roseus. Biirger's figure moreover leaves no doubt as to the identity of 

 my specimen wnth his C. roseus. 



Geographical distribution : The French coast of the Channel and the 

 Mediterranean. 



3. Cerebratulus alleni. Nov. spec. 

 Locality : Yealm sandbank. 



This Xemertine was collected on the 7th of November, 1907. The 

 single specimen was given to me last summer. It had been preserved 

 in corrosive sublimate and was then in alcohol. The only description 

 I could get of the living animal was : colour, light flesh with white 



