110 
THE VOYAGE OF H.M.S. CHALLENGES. 
transparent, the tentacles brown, the gills and protruding external generative organ 
orange, the foot dark purple.” 
The length of the specimen (somewhat contracted no doubt) is 12 cm., its breadth 
10 ’5 cm., and height 7 cm.; the length of the foot 6 '5 with a breadth of 4 ‘5 cm. ; the 
length of the tentacles and rhinophoria nearly 2 cm., and of the projecting glans penis 
1‘5 cm. ; the height of the branchial tufts nearly 1 ’5 cm. The colour of the body, 
together with the branchia, a greenish-white, the rhinophoria greenish-grey, the head and 
tentacles brownish-grey, the projecting external genitalia yellowish- white ; the quite 
narrow sides of the body and the foot black. 
The body (PI. XIII. fig. 1 ; PI. XII. figs. 14, 15) is nearly spherical in shape, some- 
what like a gigantic Onchidiopsis ; there is no trace of a dorsal margin or distinct line 
dividing the back from the sides, but near the base of the foot all round the body the 
small elevated figures of the back were entirely absent ; this region of the body is quite 
smooth, and passes anteriorly into the neck (fig. 14) ; it answers to the sides of the body in 
other Dorididse. The back 1 is very convex, densely covered with small, scarcely elevated 
disk-like figures, each with a fine aperture surrounded by an areola with a raised margin ; 
these figures are round or oval in form, the largest measuring 2 ’5 mm. in diameter ; 
towards the periphery they decrease in size (figs. 14, 15); between them were a number 
of small papillae, in height from '5 to 2 '5 mm., the former disks are no doubt the 
remains of other papillae that have been lost (PI. XII. fig. 16). At the anterior end 
are the rhinophoria, which were in this specimen fully extended, and the rhinophorial 
cavities reduced to a slightly prominent even margin ; the stems of the rhinophoria 
(fig. 14, a, a) are strong and short, their club-shaped extremities elongated, with about 
100 more or less complete narrow leaves on either side, the two series on the back side 
separated from each other by a dorsal prolongation of the stem. The flattened rather small 
branchial tufts are situated posteriorly, two on the right side and three on the left ; probably 
the missing branchial tuft on the right hand side had been accidentally lost, since the 
remains of the stem (fig. 15) were visible. Each branchial tuft consists of four unequal tri- 
or quadripinnate leaves, which diverge from a common stalk ; in the uppermost gill on the 
left side the stems bearing the small gill-leaves were separate, each bearing two leaves. 
Behind the last branchia, and completing in this way the branchial circle, is the anal 
papilla, situated in the middle line of the body, and directed backwards and downwards ; 
the anal aperture is stellate (fig. 15). In front of the anus, close to the posterior right 
interbranchial space, is the prominent renal papilla (fig. 15). The frontal margin of the 
back is but slightly developed, and has no trace of appendages, and entirely disappears 
below (fig. 14). The sides of the body are very low. The genital openings are very con- 
spicuous, and surrounded by a raised margin 11 mm. high (fig. 14); from the anterior 
1 There were two large lacerated holes on the hack (2 cm. and 1*4 cm. in diameter respectively), through which a 
great part of the liver had been lost. 
