Polychaeta. 277 



The tube consists of agglutinated particles of black and red sand. 



The prostomium has two grooves above, separated by a low keel ; 

 there is no limbus. The head is not only coalescent with the 

 achaetous buccal segment, but also with the first setigerous segment, 

 so til at the animal is provided with a long porrect neck. The plane 

 of fusion of the buccal with the first setigerous segment is indicated 

 dorsally by a peculiar transverse crest, which is apparently obsolete 

 in some, though present in most specimens. Of course the length 

 and appearance of the segments will depend upon the state of 

 contraction of the worm during preservation. 



The second and third setigerous segments are each provided with 

 a collar which embraces the segment in front ; the seventeenth to the 

 twenty-fourth setigerous segments are elegantly campanulate, the 

 bell l^ecoming deeper in the posterior segments. 



There are not more than twenty-four segments on the most 

 complete specimen, but the worm is fragile, the campanulate seg- 

 ments especially separating with great ease. 



Segments four to ten are not longer than they are broad ; from 

 the eleventh th'ey increase in length, commencing to decrease again 

 after the twenty-first setigerous segment. Segments four to nine 

 inclusive carry ventral shields {scuta ventralia). 



The uncini commence with a biserial disposition on the fifth 

 setigerous segment and become uniserial at the fifteenth.^ 



I should estimate that the total length would be about 70 to 80 mm. 



TEREBELLIDAE. 

 Sub-familY AMPHITRITEA. Malmgren. 



TlIELEVUS. 



Leuckart, 1849 ; cliar. emend. Malmgren, 1865 ; sens, ampl., Gnibe, 1877. 



a, Leuckart, R., 1819: ' Zuv Kenntuiss der Fauna von Island.' /. Arch. 



Nahirg., XV. 1, p. 169. 

 /3. Malm'ii-en, A. J., 1865: 'Nordiska Hafs-Annulata.' Of v. Ak. Fork., 



p. 386. 

 y. Grube, A. E., 1877: ' Anneliden-Ausbeute S.M.S. " Gazclhr' 



Monatsher. Ak. Berlin, p. 544. 



Branchiae filiformes, acervis transversis filorum simplicium compositae, paria 

 duo (!rAe?e/)MS, s. str.) vel {v\:y {Neottis) ; fasciculi sctarum capillariuni a segmento 

 tertio (11'° branchifero) incipientes, per segmenta numerosa (plura quam XXX) obvii. 



^ T have ascertained from material in the National Collection that the uncini 

 are uniserial in the abdominal segments of the northern type. 



