520 SIR CHARLES ELIOT ON THE NUDIBRANCHIATA 
branchial or tentacular appendages at one extremity of the body. Similarly, Elysiadae 
and Planarians are much alike in form, and constantly mistaken for one another; both 
are thin sheets of living matter, which progress by creeping and swimming. 
Notaeolidia, gen. nov. 
This new genus seems worthy to form the type of a new family intermediate 
between the Aeolididae and such forms as Dendronotus and Lomanotus. Externally 
the animals resemble the Aeolids, and are chiefly remarkable for their great size. They 
have no frontal veil, but large oral tentacles, perfoliated rhinophores without sheaths, — 
and numerous cerata, arranged somewhat as in Gonieolis. The internal digestive 
organs, however, deviate from the type of Aeolis. The portion of the hepatic system 
within the body cavity consists of a folliculate mass as well as of tubes, and lies under . 
the large hermaphrodite gland; the radula consists of a few rows (generally eighteen), 
each containing nine or sometimes eleven teeth. On the one hand, it is practically the 
radula of Coryphella and Gonieolis enlarged and extended; on the other, it presents 
resemblances to that of Dendronotus on a small scale. 
Two or three species are known. NV. gigas and N. purpurea described below are 
perhaps only varieties of one form, and differ chiefly in size and colour. NV. depressa, 
obtained by the Discovery, which will be shortly described by me, is flatter, and super- 
ficially resembles Lomanotus, as it has only a single row of cerata on the mantle margin. 
It resembles .V. gigas, however, in all essential points, and the radula is similar, though 
specifically distinguishable, the laterals being narrower and the denticles larger. 
The characters of the genus, which are at present those of the family, are as 
follows :— 
Large animals of Aeolidiform appearance. Oral tentacles large: rhinophores per- 
foliate without sheaths. Foot rounded and grooved in front. Dorsal margin un- 
dulated, and bearing one or more rows of close set cerata. Jaws not denticulate. 
Radula consisting of a central tooth and four (rarely five) laterals on each side. Central 
tooth with strong median cusp and side denticles ; laterals denticulate on inner side. 
The liver forms a lobed floceulent mass within the body cavity, and in the body walls 
a thick spongy layer, from which rise the diverticula which enters the cerata. The 
hermaphrodite gland lies above the liver. 
Notaeolidia gigas, gen. et spec. nov. 
The collection contains six specimens, which, though differing considerably in size 
and somewhat in appearance, all seem referable to the same species. The largest (to 
which the details given in the description below refer unless otherwise stated) is no 
less than 122°5 mm. long. The measurements of the others are as follows :— 
