xii SPIONIFORMIA 323 



said to ascend rivers and live in brackish water. JV. coniocephala 

 Jnstn. is much the same colour, but reaches a length of 8 inches, 

 and a diameter of ^ inch. The prostomium is conical. The podal 

 membrane reaches to the tip of the gill in the anterior segments. 

 The worm burrows rather more deeply and nearer low-water mark 

 than the preceding species. 



Fam. 2. Polydoridae. Poly dor a Bosc ( = Leucodore Jnstn.) 

 is readily distinguished from the other Spionids, and, indeed, 

 from any other Polychaet (except Chaetopterus), by possessing 

 specially strong chaetae in the enlarged fifth chaetigerous segment. 

 The anterior segments differ from the rest in the absence of gills 

 and in the character of the chaetae (Fig. 133, A, p. 261). 



P. ciliata Jnstn. inhabits soft mud tubes near low water; 

 it also makes U-shaped galleries in stones and shells, and the 

 tube projects from each mouth. The worm is about |- inch 

 long, consists of some forty segments, and is yellowish or 

 flesh-coloured. The prostomium resembles that of Spio ; the 

 peristomium is raised into a slight collar at each side. The 

 anus is surrounded by an incomplete funnel. The species has 

 almost a world-wide distribution, having been recorded from 

 Iceland, Australia, the Philippine Islands, as well as from the 

 European seas. P. coeca Oerst. often lives commensally with a 

 sponge, having a protective odour. 



Fam. 3. Chaetopteridae. The family is represented on our 

 coasts by Chaetopterus variopedatus Ken., 1 which is found at 

 the Channel Islands, the Scilly Isles, the Isle of Man, and the 

 west Scottish coast, and probably at various other places, 

 at low water and down to a depth of some 15 fathoms. It 

 occurs in all European seas. The animal builds a long tube, 

 the basis of which is a tough, parchment - like substance ; 

 this is coated externally with sand, small pebbles, and other 

 debris : it is of considerable length and about J inch in 

 diameter, is U-shaped and open at both ends, the greater part of 

 it being embedded in sand or in crevices of rocks. The animal, 

 whose body- wall is thin and delicate, never leaves its tube. 

 The body has a bizarre appearance ; three regions are readily 



1 The British species is usually referred to as C. insignis Baird, but Joyeux 

 Laffuie (Arch. Zool. Exp. (ser. 2) viii. 1890, p. 244) has shown that there is 

 only one European species. It is possible that there is a closer affinity with the 

 Sabelliformia than is at present supposed. 



