TETRERES MTJRATA. 7 



rows of spikes. Hooks long, narrow and serrated. Tube massive, of fragments of 

 shells and pebbles. 



Caullery 1 (1913) gives sound reasons for dividing De Quatrefages 5 genus Pallasia 

 into two, viz. Pallasia sensu stricto, and Tetreres? Caullery. The former has three 

 anterior " parathoracic " segments. The paleas of the external row of the crown are 

 inflected and pennate at their extremity, whilst those of the inner row are smooth and 

 fine. Tetreres, on the other hand, whilst agreeing with Pallasia in general characters, 

 differs in having four " parathoracic " segments. Palea3 of the external row more feeble 

 and more numerous than those of the internal row. Both are sabre-shaped with smooth 

 edges. 



The genus Phalacrostemma of Marenzeller, species of which come from the Azores 

 and Madeira, is a closely allied one. 



1. Tetreres murata, Allen, 1904. Plate CXVIII, figs. 1 — Id — body and tube; Plate 

 CXXIII, figs. 1 — 1 h — bristles, palea3, hooks ; Plate CXXV, figs. 8 and 8 a — 

 capillary bristles. 



Specific Characters. — Cephalic region with twenty papillae on the pillars. Palese of 

 the outer row thirty-four to forty-five, thin, smooth, straight, translucent, flattened, with 

 long tapering points. PaleaB of the inner row (about eleven visible) are stouter, stronger, 

 bright yellow, straight, flattened, and directed forward. Behind the rows of palege are 

 two stout, black hooks imbedded in fleshy papillse. Tentacles attached directly to the 

 surface of the lobes. Body about 130 mm. in length. Branchiae dark olive-green, twenty 

 to twenty-one on each side. Caudal tube dark green. Hooks with eight teeth. 



Synonyms. 



1904. Pallasia murata, Allen. Journ. M.B.A., vol. vii, p. 232. 

 1906. „ „ idem. Ibid., vol. vii, p. 299, pi. x. 



1912. „ „ Crawshay. Ibid., vol. ix, p. 348. 



1913. Tetreres murata, Caullery. Bull. Soc. Zool. France, t. xxxviii, p. 200. 

 „ Pallasia murata, Mcintosh. Ann. Nat. Hist., ser. 8, vol. xii, p. 169. 



1915. „ „ Allen. Journ. M.B.A., vol. x, p. 645. 



Habitat. — Dredged in the neighbourhood of the Mewstone and Stoke Point, Plymouth, 

 and in the English Channel. Dr. Allen states that the tubes are very common, and are 

 widely distributed over the Channel on the rough grounds. It is rare, however, that the 

 animals are secured, as the tubes appear to be buried vertically in the gravel and the 

 inhabitant can retreat downward. Common at Plymouth (Crawshay). 



The modification of the two great pillars or lobes (so-called peristomial lobes and 

 feet of others) which carry the bristles of the crown is considerable, since on the dorsum 

 a groove commences in the anterior branchial region, soon forms a broad sulcus (Pig. 

 137 a), which debouches at the point of separation of the two long grooved and obliquely 



1 'Bull. Soc. Zool. France/ t. xxxviii, p. 198. 



2 rerprjprjg, galley of four series of rowers. 



