38 
THE VOYAGE OF H.M.S. CHALLENGER. 
Mobius, &c.), north of American continent, viz., Assistance Bay (Huxley), Labrador 
(Verrill), Port Foulke (Stimpson), Discovery Bay (Duncan and Sladen). 
(Mus. Holm.) A very great number of specimens from Skagerrak, south of Arendal, 
Spitzbergen, Greenland, Nova Zembla, Sea of Kara, and the northern coast of 
Asia. Danielssen and Koren and Duncan and Sladen are of opinion that the 
forms examined by Steenstrup and Liitken are distinct from those described by 
Sars and myself, and they base their supposition on the fact that the former 
have stalked wheels, but not the latter. However, I cannot quite agree with 
them, whence I think a careful re-examination and comparison necessary. 
Though I have had the opportunity of studying a very great number of 
specimens from different localities, I never found stalked wheels, except in 
specimens which were more or less macerated, whereby the wheels become free 
from the surrounding tissue and become attached by their celitre to threads of 
connective tissue. However, it may possibly be that the animal possesses the 
capacity of protruding the wheels with their surrounding tissue beyond the level 
surface of the skin, but according to my opinion, this may he common to all 
forms. The specimens obtained at the southern localities are peculiar from the 
scantiness of wheels. 
Genus 6. Aeanthotroehus, Danielssen and Koren, 1879 and 1882. 
TentacleS'i twelve, digitate. Deposits — free, scattered wheels of two kinds ; the 
smaller with about twenty-two triangular teeth, directed inw^ards from the rim 
and generally furnished with eleven spokes ; the larger with eight to eleven 
spokes and with as many long processes directed outward from the rim. 
Spokes of the wheels with wing-like margins. 
Aeanthotroehus mirahilis, Danielssen and Koren, 1879 and 1882. 
Habitat . — Between Spitzbergen and Norway. Lat. ,73° 47' N., long. 14° 21' E.; 
depth, 767 fathoms; Biloculina clay. Lat. 71° 59' N., long. 11° 40' E; depth, 
1110 fathoms; Biloculina clay. Lat. 74° 54' N., long. 14° 53' E.; depth, 
658 fathoms ; brown and grey clay (Danielssen and Koren). 
Genus 7. Troehoderma, Theel, 1877. 
Tentacles ten, digitate. Deposits — crowded, free wheels in several superposed 
layers with the rim very spinous ; the spokes more than six, varying from ten 
to sixteen. 
Troehoderma elegans, Theel, 1877. 
Habitat . — Nova Zembla and Sea of Kara (Th4el, Stuxberg). 
