PLYMOUTH NEMEKTEANS. 409 



I. Fam. TUBULANiDAE, Burger. 



Cerebral organs nearly always present ; the cephalic furrows merely 

 consist of epithelial grooves. Often with lateral sense-organs. Nervous 

 system situated between the epithelium and the basal membrane or 

 between the basal membrane and the outer circular muscle layer. The 

 epithelium is very thick and contains many clusters of secretory cells. 

 Inner circular muscle layer present. A median dorsal blood-vessel 

 is not present. 



Genus Tubulanus. 



The nervous system is situated between the basal membrane and the 

 muscular body-wall. Cerebral organs present. 



1. Tubulanus polymorphus {Ben.). (Burger. Monogr. Taf. I, Fig. 4 ; 

 Joubin. Les Nemertiens, PL I, Fig, 8 et 9.) 



Locality : Eddystone and Eame-Eddystone Grounds ; once off the 

 Breakwater. 



A few specimens of this Nemertean were always dredged in the 

 deep water near the Eddystone or on the Kame-Eddystone Grounds, at 

 a depth of 45 m. or more. No external markings are present ; the 

 body has a uniform orange colour and is rather soft. The head is 

 separated from the body ; it is much broader and rounded. Lateral 

 organs are present. 



Geographical distribution : Norway, England, France (both coasts), 

 Mediterranean coasts. 



2. Tubulanus linearis {Mcintosh). (Burger. Monogr. Taf. I, Fig. 2.) 

 Locality : Several specimens known from different localities inside 



the Breakwater (Queen's Grounds, Asia Shoal, Millbay Pit, Duke 

 Eock). Shallow-water form. 



The head and oesophageal region of this Nemertean are milk-white ; 

 the other part has an orange-brown tint. This is due to the intestine. 

 The head is very flat, and in the living animal very often makes a 

 burrowing movement. Notwithstanding the perfect transparency of 

 this part I have not been able to distinguish the cerebral organs or 

 cephalic slits. The rhynchodaeum is conspicuous as a milk-white line 

 in front of the brain commissures, which are very long ; the brain lobes 

 are but small and do not approach each other at all. The proboscis 

 sheath does not extend into the hinder part of the body ; it is, however, 

 present at the beginning of the intestinal region. 



Geographical distribution : Southern coast of England, AVimereux, 

 Naples. 



NEW SERIES. — VOL. IX. NO. 3. JUNE, 1912. 2 D 



