TRITONIIDAE. 7 



When not otherwise stated, the following data and measurements apply to 

 specimen A (Fig. l). 



Though it is rather hard to say where the dorsal margin begins, it is clearly 

 12 mm. wide in some places, and is wavy, with two sharp, but perhaps not natural, 

 undulations inwards. Each side bears more than twenty points or papillae, the largest 

 3 mm. high. They show no sign of branching or division, but the larger bear on the 

 under surface a few folds. The oral veil is distinctly bilobed. Besides two projecting 

 grooved tentacles of the type usual in Tritonia, it bears on the right lobe, which is 

 larger, seven tubercles, and on the left lobe three, one of which is larger than the rest, 

 and formed of three small tubercles fused together. 



Fig. 1. — Tritoniella belli — Specimen A from above. 



The rliinophore sheaths are 5 mm. high and 4 mm. Itroad. The opening is not 

 crenulate, and points somewhat outwards. The dorsal margin starts from the side of 

 the sheath, which is .somewhat elongated in this direction. The rhinophores them- 

 selves are conical knoljs, surrounded by 6-8 much-divided plumes. There are a good 

 many scattered knobs on the dorsal surface, especially about the point where the 

 margin begins, though not on the edge of the flap. Down the middle of the back 

 runs a longitudinal ridge. It bifurcates just before the rhinophores, and sends off a 

 branch to each sheath. On the right, about the middle of the back, it gives ofl' a 

 T-shaped process. Between and in front of the rhinophores are four irregularly 

 shaped tubercles. A little behind the rhinophores two ridges run inwards from the 

 dorsal margin, but do not reach the median longitudinal ridge. The foot is rounded 

 in front, and very slightly grooved. The margins are not expanded in any part, and 



