414 G. WYNHOFF. 



III. Fam. cephaloteichidae. 



Bodywall composed of an epithelium in which a separate layer of 

 gland-cells does not exist, the basal membrane, the outer circular and 

 the inner longitudinal muscle layer. The inner circular muscle layer 

 often fails. The nervous system is situated in the middle of the inner 

 longitudinal muscle layer. Sense organs are not developed. Four 

 thick cephalic nerves. Vascular system consisting of a pair of lateral 

 blood-vessels only. A great number of nephridial organs. 



Genus Cephalothrix. 



Mouth widely separated from the brain. Body thread-like. No 

 sense organs. The oesophageal nerves are not paired. No bifurcation 

 of the continuation of the dorsal brain lobes. An inner circular 

 muscle layer fails. The genital sacs are not developed in the 

 oesophageal region. 



1. Cephalothrix rufifrons {Johnston). (Biirger. Monogr. Taf. II, 

 Fig. 24.) 



Locality: Common between tidemarks at Eum Bay, Mount Edgcumbe, 

 Drake's Island, the Mewstone ; in clean sand, between corallines, 

 under stones, etc. Very thin, colourless or white species, with two 

 small red or orange spots on the tip of the head. Length, 30-40 mm.; 

 breadth, J mm. 



Geographical distribution : Coasts of Norway, Denmark, Great 

 Britain, France, and Italy. 



SuBORDo II. HETERONEMERTINI. 



The body-wall is composed of the epithelium, cutis, outer longitudinal, 

 outer circular and inner longitudinal muscle layers. The nervous 

 system is situated between these muscle layers. The lateral nerves 

 are always found outside the circular muscle layer. 



L Fam. BASEODISCIDAE (= Eupolidae, Bergendal). 

 Proboscis pore near the tip of the snout. The inner muscular layers 

 are not developed in the head. Cerebral organs large, close to the 

 brain. A thick layer of connective tissue separates the epithelium 

 with its gland cells from the outer longitudinal muscle layer. Proboscis 

 with two layers, an outer circular and an inner longitudinal. Pro- 

 boscis without muscular crosses. The proboscis sheath is short. Head 

 more or less rounded ; usually with eyes. 



Genus Poliopsis. 

 Head sharply separated from the body by a deep furrow. A dorsal 

 and a ventral median longitudinal cephalic furrow are present. 



