220 SABELLIDJS. 



2 a. Abdominal hooks avicular ; thoracic dorsal bristles of two kinds — Jasmineira, 



Langerh. 



3 a. Abdominal hooks resembling the flattened plates of the Terebellids or 



Serpnlids. 



a. Branchiae forming two divisions on each side united by a thin 



membrane throughout the greater part of their extent. 



a. Without prominent uncinigerous tori. Almost complete 

 ring of minute hooks on the abdomen. Thoracic dorsal 

 bristles of one kind, Myxicola, Koch (Eriographis, Grube, 

 Arippasa, Johnst.), including Leptochone, Clpd. 



j3. Prominent tori uncinigerous. Hooks do not form a ring 

 on abdomen. 



1 a. No ventral groove in the posterior segments. 



Thoracic dorsal bristles of two kinds — Chbne, 

 Kr. 



2 a. Ventral groove in the posterior segments. Dorsal 



thoracic bristles of two kinds, rarely of one — ■ 

 Euclwne, Mgrn. 



b. Branchia3 not united by a membrane throughout the greater part 



of their length. 



a. Branchial barbules not terminated at the same level. Dorsal 



thoracic bristles of two kinds — Dialyehone, Clpd. 

 (3. Branchial barbules all terminating at the same level. Dorsal 

 thoracic bristles of one kind. 



1. With a collar — Oria, Quatref. 



2. Without a collar — Fabricia, Blv. 



Parasites. — Amongst the external crustacean parasites of this family discovered 

 by Sars, 1 are Sabelliphilus elongatus, Sars, on Sabella peniciUus (S. sarsi, Kroyer), 

 Ghonephilus clispar, Sars, on Ghone papillosa, and Sabellacheres gracilis, Sars, on 

 Myxicola Sarsii (probably M. infunolibulum) , the former from Norway, the two latter 

 from Fin mark. 



An interesting commensalistic form is Lar saMlarum, a Grymnoblastic hydroid, 

 which was originally found by Gosse growing on the edge of the tube of a Sabellid 

 in his aquarium. This peculiar hydroid has only two tentacles and a mobile bilabiate 

 " proboscis." Hincks, Browne, Dick and Gemmill have since found the same species, 

 the three last-mentioned in the estuary of the Clyde, and reproductive individuals and 

 gonozoids have been described. 



Moseley 2 and Ray Lankester 3 found chlorocruorin in Sabellidas from both deep 

 (600 fathoms) and shallow w r ater. MacMunn subsequently met with the same substance 

 in the greenish blood of Sabella. 



1 < Christ. Vidensk. Selskab. Forhandl./ 1861, p. 46 (sep. copy). 



2 ' Quart. Journ. Micr. Sc./ N.S., vol. xyii. 



3 Ibid., November, 1867. 



