Ö14 THE GENERA OF NEMERTEANS. 



(lark grey, the margins of the body are generally marked 

 off by two other white lines. A small caudal appendage 

 similar to that of other species which have formerly been 

 united in the genus Aficrura is present in most of the spe- 

 cimens. The deep red colour of the ganglion shines through 

 the pigmented tissues of the head. The urticating elements 

 in the proboscis are of different dimensions ; the smaller ones 

 measure 0.018 mm. without thread, the larger ones up to 

 0.075 mm. Eye-specks very numerous in four series, close 

 to the lateral margin of the head , two of them on the 

 ventral, two on the dorsal lips of the respiratory fissures. 

 In each series I counted from 12 — 30 eyes , the number 

 differing according to the size of the specimen. There is a 

 considerable amount of variation in the intensity of the 

 ground-colour which in some has become so dark that the 

 white lines on the back have almost totally disappeared , 

 after having passed through a reddish tinge , and that only 

 the tip and sides of the head are whitish yet. The belly 

 is very dark too in these specimens, whereas in others it 

 is white or nearly so , and in that case the coloured stripes 

 on the back have faded down to a light sienna. 



14. Cerehratulus liguricus (Blanchard) Hubr. 



Nemertes ligurica Blanchard. (Ann. des Sc. Nat. 

 XII. ser. 3.) 



By its general appearance this species may be easily 

 taken for C. inarginatus. The colour is a light grey with 

 whitish margins. Contrary to what is found in the latter 

 species, this Nemertean has eyespecks, about 12 on each 

 side of the head. In specimens which are preserved entire 

 a small translucent caudal appendage , capable of a certain 

 lengthening and shortening is often , though not always , 

 visible. In most of the specimens an extremely fine trans- 

 verse wrinkling of the skin seems to be a characteristic 

 feature. 



Notes from the JLieyden Museum. 



