380 PART II. SYSTEMATIC ACCOUNT 



length 30-6 mm; length of pre-annular part 10 mm (5-15); length of post- 

 annular part 20-6 mm (up to 39); length of proto- and mesosoma together 

 0-75 mm (0-5-1-0); length of coiled tentacles 1-5 mm (0-5-2-2). 



The preannular part of the body grows longer as the gonads and gametes 

 begin to develop. It is less than 7 mm long in immature specimens; 7-10 mm 

 long in females and 10-15 mm long in males. 



There are from two to four tentacles but two is the most common number 

 (11 specimens have 2, 3 specimens have 3, 2 specimens have 4) and the type 

 specimen has two; they are coiled together into a tight spiral inside the tube 

 and each one has a double row of pinnules (Fig. Al 52i% G). Specimens with two 

 tentacles often have a small swelling behind the base of one of them, which 

 may be the first sign of the development of a third. The protosoma is very 

 short (about one-quarter to one-fifth the length of the mesosoma) and is 

 separated from the mesosoma by a shallow groove on the ventral side only 

 (Fig. A1525). The bridle lies on a broad ridge and is not complete on the dorsal 

 side, but on the ventral side the two halves are sometimes separate (Fig. Al 525 ) 

 and sometimes joined. There is a wide groove along the ventral side between 

 the base of the tentacles and the bridle. 



The septum between the mesosoma and metasoma can be seen through the 

 body wall, but there is no external groove. The metameric region is short and 

 has only 6-13 pairs of glandular papillae (7 in the type specimen). The first 

 4 or 5 of these papillae are devoid of adhesive plates, but all the other papillae 

 on the metasoma bear small round plates (Fig. A\52E). Behind the paired 

 papillae is a long region bearing occasional isolated papillae and ending in a 

 close row of up to 15 large papillae just before the girdles. The two girdles 

 are made up of single or semi-double rows of small toothed platelets (Fig. A152 

 C, D). The post-annular region bears transverse rows of two or three papillae 

 at intervals of about 1 mm. 



Mature males contain flat, leaf-like spermatophores, with very fine 

 filaments (Fig. A1527). 



D. capillaris has the following characters in common with species of 

 Polybrachia : part of the tube is built up of short overlapping segments ; the 

 tentacles bear pinnules; both paired and unpaired trunk papillae bear 

 adhesive plates; the post-annular papillae are arranged in transverse rows, 

 and the spermatophores are of similar shape to those so far described for 

 Polybrachia. There are some differences which suggest that the new species 

 might belong to a separate, new, genus : the number of tentacles is small 

 compared with 18-73 in other species; there are no circular grooves on the 

 proto- and mesosoma, apart from the incomplete one separating the two 



