KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 39. N:o |. 59 
Colour in alcohol: whitish gray. 
Tentacles up to 100 or more, commonly fewer, in about 10 groups. 
Ventral retractors issuing from the middle third of the body; roots simple. 
Spindle-musele not attached posteriorly. 
Skin firm, smooth, shining like mother-of-pearl, finely reticulated, with very 
small, dispersed papille, not very prominent. b 
Locality: Aretic Sea. 
Phascolosoma Trybomi: Length of body: 100 mm. (proboseis from anus 40—45 mm.). 
Colour in alcohol: ligth dirty brown. 
Tentacles nearly 100, in 10 groups. 
Ventral retractors issuing from the anterior portion of the median third of 
the body; roots simple. 
Spindle-musele not attached posteriorly. 
Skin smooth, firm, not very thick, almost without structure, devoid of true 
papille, but with minute glands with pores. 
Locality: the Sound. 
Group IT, which is characterised by the possession of only two ventral retrac- 
tors, is somewhat more heterogeneous. Ph. procerum and Ph. eremita scarcely pre- 
sent any close relationship to each other, nor to the remaining species, which, on the 
other hand, among themselves constitute a quite natural subdivision. 
Synopsis of the species belonging to the "abyssorum-section"'. 
Tentacles still discernible: 
Number of tentacles 20—24. Powerful, slightly curved hooks in 
10 to 14 rings. Proboscis a little shorter than a third of the 
animal. Skin smooth, wanting papille. Retractors separate and 
issuing from about the middle of the body. Segmental organs 2. abyssorum. 
Number of tentacles 8—10. Hooks absent. Length of the animal 
30 mm. Proboscis 40 mm. Skin smooth, bright, with exceedingly 
small papille. Retractors united to the bases and issuing from 
about the middle of the body. MSegmental organs 2. . . . . Lilljeborgii. 
Tentaeles reduced to a disk with or without some inflated folds, more 
or less distinet. NSegmental organs 2. Retractors more or less 
united, attached near the middle of the body or further back. 
Hooks present. 
Papille of the skin exceedingly fine, almost inconspicuous. 
Proboscis longer than the body itself (according to DANIELS- 
SEN and KOREN twice as long as the trunk), very nar- 
row, thread-like, with numerous series of triangular hooks 
lying relose together . ..1t91 debant. fulekiltg rörd tb fsolgleciude. 
