74
has not been discovered in the Uniseriate. I t has a projecting mantle-margin and head-
shield, and the liver forms a thick layer in the integuments beneath the cerata. Himatella
too has a projecting margin. To this group may be added Goryphella, Gumanotus, and
Flabellina, which all have denticulate laterals and a radula which is practically that of
Dendronotus or Noiseolidia reduced to three teeth. Another subdivision is formed by
Galvina and Gapellinia, which have inflated cerata, a strong central tooth, and broad but
almost membranous side teeth. The radula of Hancoclcia is almost exactly similar and in
a less degree that of Hero. The radula of Ghlamylla, Goryphella, etc., is practically that
of Dendronotus or Notaeolidia reduced to three teeth.
The Uni seriate are a very large group, but offer only slight varieties of structure.
They may perhaps be grouped by the shape of the teeth as well as by any other character.
Of these teeth there are three types. The first and commonest has somewhat the shape
of a horseshoe, bearing in front a median cusp and some accessory denticles at the side.
More than twenty genera having such teeth have been described. In some the body is
slender and elongate, e. g. Facelina, P h id ia n a and Hernia (from which last Rizzolia seems
to me indistinguishable). These three forms are similar in appearance but are clearly
separated by the structure of their rhinophores,. foot, and genitalia. Other genera are
relatively short, and if not stout at least less slender. Such are Guthona, Ainphorina,
Tergipes, and others. A few have special peculiarities. Thus Embletonia has rounded
lappets on the head instead of oral tentacles.
The second type of tooth is broader than the first; the middle cusp is small or
absent, and the whole tooth assumes the form of a curved row of denticles, often very
numerous. This type appears to have been developed within the JEolididaa, and is not
known outside the limits of the family. I t clearly secures a broader denticulate surface.
I t is found in AEolidia, zEolidiella, and some allied genera which have -a further common
character in the possession of flat or compressed cerata. Perhaps Phyllodesmvum, an
Indo-Pacific form, should be placed here, as well as Gerberilla and Fenrisia. The third
and rarest type of tooth consists of a single cusp with hardly any denticles or none at all.1
I t is found only in Favorinus, which is also characterized by having a bulb under the tip
of the rhinophores. Perhaps Moridilla, which has only two lateral denticles and rhinophores
studded with tubercles, should be placed here.
There remains one genus which has such exceptional characters that it requires a
special sub-family which may be called Serrate for its reception. This is Galma,s which
is known to feed on fish-eggs. As a consequence, no doubt, of this unusual diet, the
radula has atrophied and become a continuous but notched band of chitin. The digestive
system is unusually broad and simple, as is also the kidney.
The following table shows the suggested classification of the Solids. Only Atlantic
genera are included. Those not recorded from British waters are in brackets. 1 *3
1 Observers are not agreed as to whether the teeth are minutely denticulate or smooth, but the
disagreement is itself a proof that the denticulation, if it exists, must be extremely small.
3 See p. 133 where I have explained that I regard this genus as consisting of Galma A. & H. +
Forestia Trinchese, but without Galma cavol/i/ni. Researches into this genus made by Mr. Evans
while this work was going through the press make it probable that it should be regarded as the
representative of a separate family, like Fiona and Myrrhine.
A. T riseriatje.
1. Lateral teeth usually denticulate:
[Chlamylla].
Coryphella.
Cumanotus.
[Flabellina].
2. Lateral teeth broad and membranaceous:
Galvina.
B. U niseriatge.
1. Horse-shoe teeth:
Facelina |
[Phidiana] [elongate.
[Hervia] j
Cuthona K mark;e(j;iy elongate.
AmphormaJ
fEmrbglePtfon iiaoJ erata inflated.
2. Pectinate teeth:
iEolidia.
.ZEolidiella.
(Including Spurilla and Berghia).
3. Smooth teeth:
Favorinus.
C. Serrate.
Calma.
The genus Fiona, which composes the whole family Fionidas, has the liver arranged
in two lateral canals and has branchial membranes on the cerata, analogous to the
branchiae of Bornella and Scyllsea, but forming a lateral lamina running along each papilla,
not a series of tufts. The orifices of the male and female genitalia are separated by an
interval. This resembles the arrangement found in the ascoglossan families.
The genus Myrrhine also must be allowed a family to itself. I t was created by Bergh1
for a large animal found in the Malay Archipelago, roughly speaking aeolidiform in
appearance, though even externally its leathery consistency and huge flat cerata are
distinctive. I t has no jaws, but a uniseriate radula of smooth teeth bifid at the tip and
not unlike those of Lobiger. The genitalia are imperfectly known, but both the hermaphrodite
gland and the kidney are diffuse and ramified throughout the body.
The four families known as Ascoglossa take their name from a peculiar form of
radula which they all possess. I t consists of a single row of somewhat spoon-shaped
teeth, 'smooth or denticulate on the lower edge, which do not fall off as in most
Nudibranchs but are preserved in a special sac. Very few teeth are in use at a time.
None of the genera have jaws, but some have an ingluvies buccalis. The central nervous
1 Siboga Expeditie, Opisthobranchia, 1905.