OPISTHOBRANCHIATA FROM THE ABROLHOS ISLANDS. 529 
next species. The anal funnel is strong]}' marked and protrudes between the 
hinder margins o£ the pleuropodia on the right side of the middle line. 
The integument is soft and smooth, but thrown into a series of raised areas 
of irregular sizes and shapes, separated fi-om one another by deep narrow 
grooves. The whole animal, more particularly in lateral aspect, presents a 
very characteristic appearance, recalling to some extent the appearance of 
crocodile-hide, but, as just noted, it is quite soft. 
The opaline gland occupies a well-defined region below the right anterior 
part of the mantle. It opens to the mantle-cavity by a very distinct, 
circular or slightly crescentic, single aperture and not by a series of apertures 
as in T. punctata. 
Colour. The colour of the preserved specimens is a very deep brownish 
grey with black lines running in many of the cracks, but also forming areas 
of interlacing tracery under the pleuropodia and in the caudal region. 
Professor Dakin informs me that in life the animal was of a deep opaque 
purple-green. 
Dimensions. The larger specimen measured, in the preserved condition, 
15 cm. long by 6'5 cm. wide and 6 cm. high, but of course would have been 
much larger in life, as all these animals shrink considerably when preserved. 
Judging from the type-shells named by Sowerby, one of the original speci- 
mens must have been at least a half or two-thirds as large again. If we 
take the estimate made by Eales (33, p. 12) that when preserved T. punc- 
tata rarely measures " more than a third of its length when alive," and 
assume it to apply to T. gigantea, we see that it is possible that the present 
species may reach a length of about 60 cm. (say, 2 ft.). 
Head. The head and neck-region of this form are quite well developed, 
although noticeably smaller than the body of the animal. Tlie vertical slit- 
like mouth has a large auriculate tentacle on each side. These cephalic 
tentacles do not meet in the mid-dorsal line above the mouth, but an extension 
of each forms a sort of lateral flange passing on each side of the mouth. 
The. postero-dorsal border of each tentacle is rolled, so as to form a very con- 
spicuous groove facing backwards and outwards. Below and completely 
hidden by the right oral tentacle is the penis. 
Foot. The foot is well developed, broad, and muscular. It is not sharply 
marked off from the pleuropodial lobes laterally, and in the larger specimen 
its surface presents the same " crocodile skin" pattern as the sides of the 
body. At the anterior end it is separated from the head by a well-marked 
groove, and it is expanded into large semicircular lobes which meet across 
the anterior end. This is present in both specimens, but much more marked 
in the large one, where this frontal expansion of the foot projects laterally 
almost the width of the head beyond it on each side. The hinder end of the 
foot has a similar, but much smaller, expanded lobe borne on each side of the 
caudal prolongation. 
LINN. JOUKN. — ZOOLOGY, VOL. XX5V. 38 
