The nudibranch family Dironidae. 525 
The second lateral tooth (Pl. 31 Figs. 4, 19) is very large with 
a long basal portion and a simple, strong and blunt hook. The tooth 
is strikingly flattened throughout, and is borne at the crest of the 
sides of the median groove, the position of the base being quite 
oblique to the long axis of the radula. The surface of attachment 
is also quite oblique to the plane of the tooth, so that in sections 
it appears to be almost Iying upon its side, the tips of the hooks 
converging toward the median line and interlocking above the groove. 
The epithelium of the roof of the pharynx forms a median and 
several smaller lateral folds, and is covered by a thick euticle. 
The esophagus emerges from the upper surface of the pharyngeal 
bulb, midway of its length, immediately above the middle of the 
radula, and is encircled at once by the central nervous system. The 
slender ducts of the salivary glands pass throug this loop, enter 
the esophageal wall and pass forward in it to a point opposite the 
anterior end of the radula, where they open into the buccal cavity 
near the posterior ends of the masticatory surface of the mandibles. 
Upon the posterior portion of the esophagus the ducts pass into the 
broad, lobulated salivary glands. 
The short and rather wide esophagus passes backward and 
downward and, at the anterior margin of the posterior visceral 
complex, dilates into the thin-walled stomach. This organ occupies 
the anterior portion of the complex, its lower face in contact with 
the inner surface of the foot, the left side almost, and the right side 
entirely concealed by the lobes of the liver. In shape it its quite 
similar to the mammalian stomach, the greater curvature being 
directed downward and backward, while the pylorie portion is recur- 
ved above the anterior and middle region, thence being continued 
forward as the intestine. Upon the upper anterior surface of the 
visceral complex the intestine describes a loop to the right and 
passes obliquely downward and backward to the ventral surface of 
the complex, along which it passes in a gentle curve to the left, 
terminating in the rectal portion and the anus at the extreme 
posterior end of the complex. Thus the intestine is exposed along 
the upper, right and lower faces of the complex through its whole 
extent, while the stomach is covered by the lobes of the liver and 
the hermaphroditic gland, save at the anterior face of the complex, 
its pylorie end and a small area on the left side. 
The wall of the esophagus is thick and muscular and is folded 
longitudinally, while that of the stomach is thin and smooth. The 
