124 
THE VOYAGE OF H.M.S. CHALLENGER. 
of the usual kind. Neither the leaves of the rhinophoria nor the skin contain any 
hard cells, and there are very few in the interstitial connective tissue. 
The buccal tube is yellowish within ; the outer surface being whitish, with fine blackish 
spots ; it is 4 mm. long ; the strong retractor muscles have many heads. The strong 
buccal cone (“ Schlundkegel”) is as long as the buccal tube, and fills it; it is yellowish ; 
the opening at the summit as usual ; 1 the interior of the buccal cone is also yellowish, 
with grey spots ; the prolongation of the bulbus pharyngeus as usual only loosely 
fastened to the walls of the buccal cone. The ptyaline gland 2 is about 7 mm. broad, 
2 mm. thick, and 4 mm. long ; it lies beneath the anterior part of the bulbus pharyngeus, 
in front of the anterior genital mass ; it is whitish in colour, and formed of two halves 
intimately united, and divided into many lobes by deep furrows. The efferent duct is 
formed of two chief branches, and is thick and coiled, it runs towards the buccal cone, 
becoming gradually thinner ; when unrolled it measures 1 2 mm. ; it runs as far as the end 
of the buccal cone. The bulbus pharyngeus, including the portion enclosed within the 
buccal cone, is 2 cm. long by ‘5 mm., increasing to 1*3 mm. in thickness ; yellowish-white 
and cylindrical, the lumen is arrow-shaped throughout the whole length. The whitish- 
yellow oesophagus is long, sausage-shaped, with numerous constrictions ; it is 2 cm. long 
with an average diameter of 2 ’5 mm., which decreases in front to 1 mm., and behind to 
1 ‘5 mm. ; the walls are thick ; the interior has retiform folds. The connective tissue of its 
sheath is not pigmented. At the junction of the oesophagus and bulbus are the 
salivary glands, 1 mm . long by '4 mm. in thickness, and faintly yellow coloured. The 
hinder end of the oesophagus is a little constricted, and then passes into the stomach, which 
is short, enclosed within the liver with the exception of the anterior end ; the stomach 
is connected beneath with the wide cavity of the liver and above with the intestine. 
This latter projects somewhat just before the middle of the length of the liver and to the 
left, forming at its anterior end a short arch, and running in a groove upon its surface 
reaches the median line and mounts between the two heads of the retractor branchiae 
muscle; its total length is 2 - 5 cm. and breadth 2-2 ’5 mm. ; its inner wall has longitu- 
dinal folds. — The hinder visceral mass [liver) is 2 - 2 cm. long by 1'8 cm. broad and 1*4 cm. 
high ; its somewhat excavated broad facetted anterior end is obliquely truncated from 
the left towards the right side and downwards and backwards ; the hinder end is rounded, 
with a deep narrow cleft, through which the strong retractor muscle of the branchia 
passes ; this cleft is continued on the under side of the fiver into a median superficial 
furrow. On the surface of the liver in front there are on either side two or three deep 
perpendicular furrows. The colour of the liver outside as well as inside is greyish. 
The alimentary tract and cavity of the liver contained a mass of undeterminable animal 
remains. 
1 Loc. cit., 1880, p. 304, Taf. i. fig. 1 . 
2 Cf. Bergh, On the Nudibr. Gastr. Moll., I., loc. cit., 1879, p. 143 (87). 
