410 DR S. F. HARMER AND DR W. G. RIDEWOOD ON THE 



branch, however, the ostia are more crowded. Length of zooids from the free ends of 

 the arms to the end of a fairly extended body, 4 '5 mm. ; length from base of arms to 

 end of body, 3'2 mm. ; width of body, '8 mm., but if the body is much contracted its 

 width is that of the tubes, i.e. 1 mm. Arms usually nine pairs, but often fewer and 

 exceptionally more ; no end-bulbs with refractive beads. Stomach and the succeeding 

 U-shaped intestinal loop long. Females not known ; and no buds having more than 

 five pairs of arms have been found. 



MATERIAL. 



The specimens of Cephalodiscus submitted to us for study were sent in six bottles, 

 five of which were of 2^ litres capacity, and the sixth of about half that size. This 

 material was dredged on December 1, 1903, and was obtained in a single haul on the 

 Burdwood Bank, to the south of the Falkland Isles (Station 346 ; lat. 54 25' south ; 

 long. 57 32' west; fathoms 56). The contents of the trawl on this occasion 

 amounted to about half a ton,* the largest and richest catch of the expedition ; and 

 the members of the staff worked up to two o'clock in the morning sorting and bottling 

 the specimens. All the Cephalodiscus material was preserved in alcohol, and no 

 special measures were taken for killing the zooids in an extended condition. 



CCENCECIUM. 



The distinguishing feature of the present species, the agglutination of foreign 

 particles in the soft substance of the crenoecium, is apparent at a glance, and the 

 semitransparent or translucent appearance of the co?noecium of other species of 

 Cephalodiscus is only to. be detected in certain parts of branches where the 

 inclusions are more scanty than usual. The general appearance of pieces of colony 

 is whitish or whitish yellow, with dark spots which mark the ostia or openings 

 of the tubular cavities inhabited by the zooids (text-fig. 1, A and B). The branches 

 are massive, resembling those of C. nigrexcens in size and bulk. The substance of 

 the branch is weak and easily crumbled, the included shelly particles adding to 

 the weight and not adding to the strength of the coenoecium. A branch taken out of 

 alcohol and held horizontally in the hand by one end breaks across by its own weight. 



The majority of the pieces of colony are about 80 to 90 mm. in length, and 

 oval in cross section, measuring about 30 mm. in the long diameter and 20 mm. 

 in the short diameter. Some of the small pieces measure about 70 mm. by 20 mm. 

 by 15 mm. The largest pieces measure about 100 to 115 mm. long, and have three 

 or even four branches. The total width of such branching pieces of colony is 

 45 or 55 mm. On Plate I. are represented five pieces which are the largest in the 

 whole collection and best suited for showing the characters of the branching. Since 

 these are drawn of the natural size, a detailed description of them individually is 



* Report of the Scientific Results of the Voyage of the S.Y. "Scotia," 1902-4, vol. iv., Zoology, part i., Zoological 

 Log, 1908, p. 61. 



(ROY. soc. EDIN. TKANS., VOL. XLIX., 534.) 



