83 



circular, and are easily distinguished from those of Dodcaiccrid 

 or Polvdoni. PoiauiiUa iriiiforiiiis not only frequents north 

 European shores, but extends to Iceland, Greenland, America, 

 ISIadeira, and the Canaries, so that its occurrence at the Cape is 

 less remar-kable. 



BiSPiKA VOLUTACORNIS, Montagu, 1808. 



1808. Aiiipliitritc roliitdconiis, Montagu, Lin. Trans. VII.,, 



tab. vii., f. 10. 

 1865. Disivlia voliiicicoi iiis, De Quatrefages, Anneles, II., p. 



421,. PI. 20, f. 5-7. 

 189-}.. Bispini 7'ohifiicoriiis, De St. Joseph, Ann. Sc. Xat. 8e. 



Sen XVII., p. 286, PI. xi., f. 289-295. 



A gigantic form (Plate viii., fig. 50) which in spirit measures 

 fullv 130 mm. with a breadth at its widest part of 17 mm. 



Anteriorly a wide gap exists between the edges of the collar 

 which are close to the first bristle-bundle. The collar expands 

 in the middle line ventrally and is reflected, the left overlapping 

 the right flap. Dorsally an elevated fold on each side of the 

 middle hne is sometimes formed between the edges of the 

 collar — apparently bv contraction. De St. Joseph describes 

 the collar as of a deep violet with a border of white in the 

 French examples. 



The anterior region consists of eight segments. On the ventral 

 surface of tlie third bristled segment on each side of the middle 

 line are two elongated slit-like marks, and they are distinct as 

 far back as the eleventh segment. 



De St. Joseph found considerable variability in the thoracic 

 segments, the number ranging from six to eleven, and, more- 

 over, the sides are sometimes unequal, e.g., seven on the left and 

 eight on the right. 



The dorsal tentacles (/'^///>c'.s De St. Joseph) are long, flattened 

 (with a thicker and a thinner edge) tapering processes, and 

 from the tuiter edge of each the web at the base of the branchiae 

 l^egins. The branchiae are rolled in a spiral of great complexity 

 on each side. The outer whorls have longer filaments, the 

 central have shorter, and in addition to the ordinary filaments 

 a series of almost pectinate folds occurs in some at the dorsal 

 edge of the whorl where the rim joins the tentacle. The central 

 whorls are very short. In all there are not less than 260 

 filaments with their pinna> which are rather short. The whole 

 system is beautifully variegated. Thus a purplish belt marks 

 the web, each filament having several touches of browaiish 

 purple alternating with pale regions, whilst the tips of many are 



