220 THE GENERA OF NEMERTEANS. 



of specimens and in a smaller number than Grube indicates. 

 In the yellow variety the red ganglion is very well visible 

 through the integument ; better so than in the white. The 

 urticating elements in the proboscis measure about 0.006 to 

 0.007 mm. (thread excluded). 



26. Cerebratulus fasciolatus (Ehrenberg) Hubr. 

 Synon. Micrura fasciolata Ehrenberg. 



Cerebratulus geniculatus Grube. 

 Meckelia knerii Diesing. 

 Cerebratulus geniculatus Ulianin. 



Dark greenish with white rings at regular intervals. 

 Anterior part of the head white with a small number of 

 eye-specks. The red variety figured by Mac Intosh was not 

 noticed at Naples. A caudal appendage was never wanting ; 

 a small specimen of 20 mm. carried ripe eggs already, 

 and so the question arises whether perhaps at Naples 

 this species ever attains the size it does in the Atlantic. 



Familia Langiaidae mihi. 



The margins of the body are slightly frilled and lapped 

 up over the back, which takes the aspect of a partly 

 closed tube from the head to the tail. Internally the ner- 

 ve-trunks lie more above the intestine than beside it. 



Genus Langia nov. gen. Characters as in the family ; the 

 openings of the watervascular system are situated dorsally , 

 in the hollow space enclosed between the upturned body 

 margins. 



27. Langia formosa n. sp. 



Belly of a pale vermilion , margins of the body whitish , 

 back posteriorly yellowish. Especially in the anterior part 

 of the trunk the upturned , frilled body margins have thick 

 borders , posteriorly they diverge now and then , showing 

 the yellow colour of the intestine shining through the 



Notes from tlie Leyden ZMuseutn. 



