Descriptions of new Metanemerteans. 11 



T. vermiculum reaches about 15 mm in length. The distance 

 between the anterior and posterior ocelli is but little greater than 

 that between the two eyes of a pair. A stripe of reddish-brown pig- 

 ment, which is sometimes abscnt, encloses on eaeh side of the head 

 the anterior eye, but seldom extends to the posterior one; there are 

 no pigment markings behind the head, but the whole body is of a 

 yellowish or orange color. 



The sexes are separate; the number of ova in each ovary varies 

 from one to three. 



This species I found very abundant at Newport, on sea-weeds 

 and Bryozoa, between tides. 



7. Tetrastemtna catenulattim (Verr.)- 

 = T. vermiculum catenulatum Verr. 



In a previous contribution ("On the Connective Tissue and Body 

 Cavities of the Nemerteans, with Notes on Classification", in: Zool. 

 Jahrb., V. 10, Anat., 1896) I have shown that this form must be 

 separated from T. vermiculum, for the following reasons : 1) the inter- 

 stitial tissue, and not the supporting cells of the body epithelium is 

 the seat of the pigment; and 2) there is not only a pigment mass 

 between the eyes, but irregulär pigment mottliugs are present on 

 each side of the dorsal surface of the body (Fig. 16). Otherwise 

 T. catenulatum closely resembles T. vermiculum. 



Abundant at Wood's Holl, on sea-weeds below low tide, on piers 

 and stones. 



8. Tetrastenima fiagellatum n, sp, 



This new species differs from the preceding two forms, in the 

 following points: 



The eyes occupy the corners of an elongated rectangle; the 

 distance between the two eyes of the anterior pair, equals that be- 

 tween those of the posterior pair ; but the distance between the two 

 eyes of a pair, is scarcely more than half the distance between the 

 anterior and posterior eyes. 



The head is not wider than the neck, truncated anteriorly. 



Sense hairs occur at both ends of the body. 



The central stilet of the proboscis is noticeably larger than its 

 basis. 



Streaked masses of reddish-brown pigment occur between the two 

 eyes of each pair, this pigment sometimes nearly fillingjthe whole 



