OPISTHOBKANCHIATA FROM THE ABROLHOS ISLANDS. 565 
is large. The braachise and sometimes the rhinophores are protected by 
valves. The rhinophores are not perfoliate. There is no labial armature of 
rods or spines, but a chitinous ring may be present. No rachidial tooth is 
present ; the pleurals are similar and hamate with indications of an accessory 
denticle. 
Species Notodoris gaedineri Eliot, Fauna & Geog. Maldive and Laccadive, 
vol. ii. pt. 1, 1903, p. 548. (PL 28. figs. 18, 19 ; PI. 30. figs. 62-64.) 
Bodi/. The body is limaciform and covered with small tubercles, which are 
more numerous and larger at the anterior end. Nearly halfway back the 
body reaches its highest point, and here arise the branchiae covered by their 
three characteristic protecting valves. A row of larger tubercles runs from 
the sides of the oral veil to the branchial valves. Beyond this the body 
falls to a lower, narrower, tail-like region. A well-marked valve-like 
tubercle lies on the outside of each rhinophoral aperture, and between these 
openings is a group of two or three large tubercles. Lateral to the rhino- 
phores the notseum passes out and forwards as a very well-marked oral veil 
with a tuberculated margin. The very tough skin contains a number of very 
hard, semi-transparent spheres, which appear to be composed of a chitinous 
material. They are irregularly scattered, and may be sparse or so close 
together that they form hard masses. 
Colour. According to the coloured sketch made by Professor Dakin, this 
species is of a deep chrome-yellow all over ; the oral veil and branchial . 
valves are of the same colour. There was apparently no trace of the black 
spots described by Eliot. 
Dimensions. The specimens were all about the same size and measured 
when preserved 43 mm. long by 9 mm. wide by 10 mm. high ; length of the 
tail-region 18 mm. Eliot's specimen was 33'5 ram. by 9 mm. by 12 mm. 
Head. The head is small and in the specimens completely hidden between 
the front end of the foot and the overhanging oral veil. This veil is very 
well developed, and in all the specimens is tightly curled down over not only 
the head but also the anterior end of the foot. 
Foot. The foot is fairly broad and lanceolate. The front end is rounded 
and the hinder end passes off to a point. 
jRhinophores. The rhinophores are completely retractile within deep 
cavities. The aperture is in the form of an oval slit placed at an angle of 
about 45° to the main axis of the animal. At the posterior outer corner of 
the aperture lies a very large tubercle whose flap-like apex overhangs it. 
Brancliice. The branchise are fairly numerous, very small, and completely 
hidden by the three lar^e valves. The three valves rise from a transverse 
ridge stretching across the middle of the back. The middle one passes back 
and curls downwards until it practically touches the dorsum. The lateral 
valves pass backwards, down and round partly forwards again, forming the 
commencement of a spiral. They also practically touch the dorsum. All 
