136 
THE VOYAGE OF H.M.S. CHALLENGER. 
Thy one poucheti, Barrois, 1882. 
noibitat, — West coast of France (Barrois). 
This species, if it be really distinct, seems to be one of the nearest relatives of Thyone 
raphanus, from which it differs mainly in the calcareous plates being of a more 
irregular form, and provided with knobs on their upper surface. “ Porcupine ” 
Expedition dredged one specimen at Station 6, 1870, from a depth of 358 
fathoms, which may probably be referred to this form. The form of the body, 
the anal teeth, &c., are like those in Thyone raphanus, but the skin is rougher. 
The deposits partly resemble those described by Barrois, being irregular and 
plate-like with numerous holes and small knobs ; a few become seale4ike in 
that the knobs are united so as to form a thicker reticulate network composed 
of superposed layers. Length 2,0 to 30 mm. 
III. Calcareous ring composed of ten pieces, each made up of a number of 
small parts ; posteriorly it carries five bifurcate prolongations. 
Thyone huccalis, Btimpson, 1856; Semper, 1868. 
Deposits — closely crowded, oval knobbed buttons with four .holes. Calcareous ring 
very long, composed of numerous small pieces, and sending posteriorly five long 
slender, bifurcate prolongations. 
Habitat. — Port Jackson (Stimpson), Rockhampton and Port Mackay (Semper), (?) Port 
Denison (Bell). 
(Mus. Holm.) Two specimens from Rockhampton. Body fusiform, indistinctly four 
or five angled. Mouth with five ridges like that in Golochirus. Tentacles ten, 
three or four ventral smaUer. Anal teeth minute. Pedicels equally distributed 
aU over the body, the dorsal apparently running out from low warts. Cal- 
careous ring made of a great number of small pieces, carrying anteriorly ten 
shorter processes and posteriorly five long slender bifurcated prolongations. Six 
to eight Polian vesicles and numerous small madreporic canals. Body-wall thick 
and hard from crowded oval buttons, which are knobbed round the margin, and, 
as a rule, pierced with four holes; an arch rises vertically to the buttons them- 
selves from each surface. Some of the buttons much smaller and more finely 
constructed. Pedicels supported by large curved rods, enlarged and perforated 
with several holes at the middle, and even pierced at the slightly dilated ends ; 
some of the rods are three-armed. Terminal plates are also present in the 
pedicels. Length of the largest specimen 75 mm. Colour in alcohol, darker or 
lighter brown ; tentacles blackish. 
The species completely resembles Thyone sacella, excepting that the latter is devoid of 
anal teeth, which are present in Thyone huccalis, thou^ they are very rudi- 
mentary. Possibly they may be proved to be identical. 
