152 NICOLE A VENUSTULA. 



largest examples was procured by the " Porcupine " in 1869 twenty-five miles off shore 

 (Ireland) ; off Fermain Bay, Guernsey ; Plymouth (Spence Bate andB. Rowe, Crawshay); 

 Kingstown and various stations on the West Coast of Ireland (Southern). The species 

 ranges to deep water off the various shores of Britain, e. g. off the Hebrides in its tube 

 inside a valve of Pecten opercularis (J. G. J.) ; Firth of Forth (Cunningham and Bam age). 

 Abroad it is found at Behring's Sea (Marenzeller) ; Spitzbergen (Fauvel, Meyer) ; 

 Christiana Fjord, Norway (Malmgren and Norman) ; Denmark and Sweden (Grube and 

 Malmgren) ; North Sea, Mediterranean (Claparede, Grube, Marenzeller) ; shores of 

 France (De St. Joseph) ; shores of Cantabria (Rioja) ; Red Sea (Boutan) ; Greenland 

 (Michaelsen) ; Franz-Joseph Land (Augener) ; White Sea (Ssolowiew) ; Antarctic Sea 

 (Ehlers)'; N.E. America (Moore). 



The cephalic collar forms a small rim dorsally and behind it is a row of distinct eye- 

 spots. The anterior border makes a spout-shaped aperture by forming an arch over 

 the mouth, and which, seen from the dorsum, narrows a little in front, whilst in lateral 

 view it slopes from above downward and backward. The tentacles are numerous and 

 have the median groove so characteristic of such organs. Ventrally the dorsal collar 

 terminates in spirit-preparations in a narrow edge at each side, the central region being 

 occupied by an independent bilobed and often spout-like flap, making a kind of 

 lower lip. 



The body (Plate CXII, fig. 5) is enlarged in front, though in the small specimens 

 this is slightly marked, and tapers to a moderately slender tail, at the tip of which is the 

 anus surrounded by blunt papillae. The segments vary from forty to fifty-five. The dorsal 

 surface is rounded, the ventral has thirteen or more shields in front, and the median 

 line thereafter is marked by a deep groove. Of a pale brown throughout, sparsely 

 speckled with white spots, except on the ventral scutes. Tentacles pale reddish. 



The branchia3 are two on each side, and vary much according to the age of the 

 specimen, young forms having only short stalks without divisions, whereas adults have 

 the branchiae well developed and more or less dichotomously divided, with short 

 terminal branches. The anterior gill is the larger and is in the adult densely arbuscular. 

 All intermediate forms occur between the one stage and the other. The best developed 

 branchiae occur in those from deep water, c. g. 80 fathoms off North Unst, Shetland, 

 and from the " Porcupine," the first pair having a comparatively long stalk before 

 splitting into the terminal tuft. The disproportion between this and the second pair is 

 marked, the latter being a short proces-s with only a few divisions. In the blood are 

 haematin-corpuscles which emit pseudopodia (Cuenot, De St. Joseph). 



On each side are seventeen bristle-bundles (Plate CXXVI, figs. 2, 2 a and 2 a') consisting 

 of translucent bristles with shafts which slightly diminish towards the upper end, where 

 the narrow wings commence and continue on the somewhat long and finely tapered tips for 

 a considerable distance, disappearing, however, on the hair-like extremity. The tufts 

 differ from those, e.g., of Amphitrite gracilis, in being single, no shorter series occurring 

 as in other types. The first bristle-bundle is found behind the second branchia and it has 

 no special appendage, but the two following have on the dorsal side of the setigerous 

 process, and continuous with it, a lanceolate appendage like the branchia of Aricia. The 

 pinnules characteristic of the posterior region commence about the twenty-first segment. 



