REPORT 0^ THE NUDIBRANCHIATA. 
43 
and Bornella cirborescens from the Southern Sea). 1 It comes nearest, however, to the 
last-mentioned of the three, hut differs sufficiently in the form of the dorsal papillse and 
the character of the branehhe and their appendages ; it agrees with these last two species 
in possessing denticulated median plates in the radula, hut the shape of the spines of 
the penis is quite different. 
Family Thitoniada:. 
This Family is in some respects intermediate between the kladohepatic Nudibran- 
chiata (iEolidiadse) and the holohepatic Nudibranchiata (Dorididae), but presents more 
affinities to the former group. "With the latter it agrees in the possession of a simple 
unbranched liver, and in the absence of a sanguineous gland and of a spermatocyst. 
It contains but few types, which differ but slightly from each other, both as regards 
outward form and internal structure. 
The body is elongated and slightly quadrangular, the anterior portion is broader, the 
posterior narrowed ; the dorsal surface is flattened and granular in appearance ; the sides 
of the body are high and perpendicular ; the foot is broad. At the anterior extremity 
the back acquires a crescentic prominence — the frontal veil ; the free margin of this is 
covered with small papillse, or with simple, sometimes compound, finger-shaped processes ; 
the outer extremity is thickened and forms a spoon-shaped structure — the tentacle 
proper. The rhinophoria are situated on the “ neck,” just behind the frontal veil. The 
sheath of the rhinophoria is tubular and slightly depressed, with a recurved margin ; the 
sword-knot-shapecl club is retractile, the central portion has a flattened upper surface, 
the margin is set with erect feather-like processes, the rhachis of the hindermost 
process is continued into a rather strongly developed papilla. On the slightly prominent 
margin of the back there are a number of variously sized branchial tufts, arranged one 
behind the other in a single series ; they are low, more or less arborescent, tri- or quadri- 
pinnate, and are set on a short stalk. The ancd papilla and the renal aperture are 
situated close to each other about the middle of the body on the right side. The foot 
is rather broad and rounded at its anterior end ; the tail is very short. 
The bulbus pharyngeus is strongly developed, and resembles that of the Pleurophylli- 
diadse, as do also the mandibles especially. The tongue is well developed ; the radula 
consists of a median tooth, on each side of which is a longer ( Tritonia ) or a shorter 
( Ccmdiella , Marionia ) series of uncinate lateral teeth; the first lateral tooth always 
differs from the rest. The stomach is generally unarmed, but in Marionia it is provided 
with a belt of hard longitudinal plates. The liver is large, and forms a short conical 
mass ; the anterior part either shows traces of becoming separated from the rest or i3 
actually separate [Marionia). The liver sends off no branches into the dorsal papillse 
1 For a description of these species, see Bgh., loc. cit., pp. 289, 301. 
