DITRUPA. FILOGRANA. 273 



inch or rather more in length, of which the branchiae may make a 

 sixth part. These organs are equal in size, fan-shaped, the filaments 

 originating from a cartilaginous base, barred with blue, with white, 

 with deeper blue, and spotted with golden-yellow in regular series. 

 The thorax is reddish on the sides ; the tapered abdominal portion 

 pale. — The base of the tube is not flat and expanded, but in other 

 respects it resembles S. triquetra, from all varieties of which it is 

 distinguished by the operculum. This it is not easy to describe. A 

 short stalk enlarges upwards,* and is continued into an oblique knob- 

 like head with a cinereous pad on one side, roughish, and furnished 

 with three minute spines. On the other side, at the separation 

 between the stalk and head, there originates a fleshy process which 

 almost reaches to the summit of the head, and is continued into the 

 stalk below, so as to form a part of it. 

 («) Berwick Bay, Br. Johnston. 



47. DITRUPA*. 



Ditrupa, Berkeley, Zool. Journ. v. 426. 



? Placostegus, sp., Philippi, Wiegm. Arch. i. 192 (1844). Grube, Fam. 

 Annel. 91? 



Char. Branchiae twenty-two, in two sets, not rolled up spirally, 

 flat, broadest at the base, feathered with a single row of cilia : mantle 

 rounded behind, slightly crisped, denticulated in front, strongly 

 puckered on either side : fascicles of bristles six on each side. Oper- 

 culum fixed to a conical, pedicellated, cartilaginous body, thin, testa- 

 ceous, concentrically striated. Shell free, tubular, open at each end. 



1 . D. subulata. 



Dentalium subulatum, Deshayes, Monog. 53. 

 Ditrupa subulata, Berkeley, Zool. Journ. v. 427. t. 19. 



Hab. Deep water. North-west coast of Ireland, Capt. Fidal, R.A. 



48. FILOGRANA. 



Filograna, Berkeley, Zool. Journ. 1827, 229; 1835, 426. Grube, 

 Fam. Annel. 94, 139. 



Char. Branchiae eight, filiform, of which two bear an infundibu- 

 liform, obliquely truncated operculum : mantle rectangular : fascicles 

 of bristles seven on each side. Shell very slender, filiform, gre- 

 garious. 



1 . F. implexa. 



Filograna implexa, Berkeley, Zool. Journ. 1827, 229 ; 1835, 427. t. f. 

 Sars, Faun det Lief. i. d>(3. t. 10. f. 12-19. Grube, Fam. Annel. 94. 



* From Sh, bis, and Tpvira, foramen. 



