OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 525 
The rhinophores bear about fifteen perfoliations, which become less distinct at the top. 
The dorsal margin makes five distinct undulations, so that the cerata appear to be set 
in groups. But this is not really the case, the arrangement being as in N. gigas, 
though perhaps the line of cerata is thinner and the bare space in the middle ofthe 
back larger. There are a few large cerata inside the line. The longest measure 16 mm., 
but most are short. 
The internal anatomy is as in NV, gigas. It is hard to formulate any real difference 
for the radula (18x 4.1.4), but perhaps the denticulation of both the lateral and 
rhachidian teeth is more distinct, and the innermost denticles of the latter are set 
higher up on the side of the central cusp. 
1 am doubtful if this form should be regarded as a separate species, or merely a 
variety of N. gigas, but its general appearance and colour are different; it is much 
smaller, though apparently sexually mature, and the oral tentacles are proportionately 
longer. 
Tiitonadae. 
This family comprises the genera Tritonia and Marionia, the former without stomach 
plates, the latter with them. To them, I think, should be added Atthila, which Bercu 
makes the type of a separate family. It appears to me difficult to maintain the dis- 
tinction between the genera Tritonia, Cuv., and Candiella, Gray. According to Brereu, 
the “margo veli frontalis” is in the former “ papilligerus” and in the latter “ digitatus”’ : 
the former has many and the latter few lateral teeth. Yet Tritonsa exsulans, Bergh, 
has 8-9 “ einfache Finger” on each side of the frontal veil and a radula with a formula 
of about 41 x 61.1.1.1.61, whereas Candiella ingolfiana, Bergh, has “six fingers” on 
each side of the veil and a radula of 67 x 83.1.1.1.83. I am, however, inclined to add to 
the family two new genera, Tritoniopsis and Tritoniella. The former, described below, 
has a divergent radula. Tritoniella, which I propose to describe among the nudi- 
branchs found by the Discovery, resembles Tritonia in most points, but has dorsal 
ridges, and instead of ramose branchie, simple projections or crenulations. Some of the 
Specimens are exveptionally well preserved, and it seems clear that no appendages are lost. 
Bereu’s list of Tritonia and Candiella in the System der Nudibranchiaten Gaster 0- 
men contains sixteen species, to which the following HEN since been added :— 
17. TL. diomedea, Bergh. 
18. Z. exsulans, Bergh. 
19. T. incerta, Bergh. 
20. T. gigantea, Bergh. 
21. 7. (candiella) australis, Bergh. 
. 22. T. (candtella) ingolfiana, Bergh. 
23. T. (candiella) villafranca, Vayssiere. 
24. T. appendiculata, sp. nov. 
