108 
THE VOYAGE OF H.M.S. CHALLENGER. 
flattened, with a deep dorsal furrow ; the yellow-coloured radula has sixteen series of 
teeth, the four anterior of which were incomplete, on the apex of the tongue there were 
traces of two other series that had become detached ; further back, beneath the tectum 
radulse and within the radula-sheath, were thirteen developed and three undeveloped 
series, — the total number being thus thirty-two. In the fifth series of the tongue there 
were seventy-six teeth on each side, and the number appeared not to increase much further 
back. The colour of the teeth is a clear chitinous yellow. The heights (PI. III. figs. 22, 
25) of the outermost (behind on the tongue) are about '056- , 07-'075- , 08 mm. ; the height 
then gradually increases to about ’12 mm., and then decreases again to- - 8 mm. (fig. 21). 
All the teeth are of the usual simple form (figs. 23, 24), with the usual “ winged ” 
base ; the outermost being more upright, with shorter base (figs. 22, 25, aa). 
The salivary glands are yellowish and long (5 mm. by '7 mm. broad), reaching to the 
under side of the stomach ; in shape flattened and band-like ; the efferent ducts short. 
The oesophagus is short and wide, about 4 ’5 mm. long, with strong folds on its inner 
surface, which end obliquely at the cardia, but are prolonged into the stomach, where they 
are much more slightly developed. The stomach is large, about 6 mm. long by 4 mm. 
broad, and reaches as far as the bulbus pharyngeus. The alimentary tract was full of the 
remains of sponges and corallines, and other unrecognisable animal debris. The intestine 
arises from the anterior margin of the stomach, and runs straight backwards ; its length is 
about 13 mm. and diameter ‘75 mm. 
The liver is about 7 '5 mm. long by 5 mm. in breadth and 5 mm. in height ; the broad 
anterior portion is obliquely truncated downwards, and is excavated to receive the hinder 
end of the stomach ; the narrower hinder end is rounded. The colour of its upper surface 
is a clear grey, the tissue itself is dirty yellow coloured ; the cavity large and round. 
I could find no gall-bladder. 
The heart is large, the ventricle 2 mm. long. The blood gland lies behind the central 
nervous system, and is oval in form, whitish in colour, and slightly lobulatecl at its outer 
edge ; its length is 2 '4 mm. — The renal syrinx is yellowish-white, melon-shaped, and 1 mm. 
in greatest diameter, with strong interior folds visible from the outside. The kidney is 
strongly developed. 
The hermaphrodite gland covers the liver ; it contained no developed genital pro- 
ducts. The duct takes its rise above the cardia ; its ampulla is yellowish- white, and 
forms a slight swelling. The anterior genital mass was somewhat undeveloped, of an oval 
compressed form, barely l - 5 mm. long, and whitish in colour. The vas deferens is not 
long ; the penis is unarmed. The state of the vesiculse seminales I was unable 'to observe. 
"Whether this animal really belongs to the genus Thordisa or not must be left uncer- 
tain for the present. The smoothness of the body, and the shape of the outermost 
plates, seem to make the generic position of the animal somewhat doubtful. 
