belonging to a new Order of the Class Cirripedia. 807 
which can be closed or opened at the will of the animal ; in front 
they gradually blend with the mantle, behind they are deeply 
notched, and each terminates in a projecting, slightly curved 
point, d. The external surface of these valvular lips is furnished 
with numerous, minute, irregularly disposed, rather stout, curved 
spines, very transparent and of a crystalline appearance. The 
circular, depressed, dise-like portion of the animal, corresponding 
to the pedicle of the pedunculate Barnacles, is slightly arched 
below, where it is pale, soft, fleshy, and as highly contractile as 
the anterior portion or head: the upper surface is flat, and has 
in the centre a broadly ovate, horny plate (figs. 3 & 5 e), most 
distinct in old individuals, but never entirely covering the part, 
the margins always extending beyond it. This plate is of a red- 
dish horn-colour, and is generally furnished with a few indistinct 
radiating ridges and tubercles corresponding to the radiating 
lines and punctures seen on the surface of the matrix. 
The animal, as before stated, lies immediately below the sur- 
face of the matrix, and is entirely free except at a point just be- 
hind the slit, g, and in front of the horny plate where there is a 
strong muscular attachment to the upper wall of the chamber. 
The longitudinal opening of the animal corresponds to the slit 
on the surface of the matrix: this opening is kept pretty accu- 
rately plugged by the thickened valvular lps of the animal, ex- 
cept when it is in watch for its prey, at which time a slight 
opening in front permits the passage of the prehensile arms 
(Pl. VIII. figs. 3,6 &-7f, d& e, and Pl. IX. fig. 1). These 
occupy the same position within the head or neck as they do in 
the valvular part of the pedunculate Cirripedes, beg placed 
immediately in front of the mouth. They differ however consi- 
derably from those of all other Cirripedes. The arms of this 
animal are only six in number ; they are short and set im a circle 
on the extremity of a soft, fleshy, cylindrical pedicle (fig. 6 ¢), 
which is undoubtedly a prolongation of the true body of the 
animal; the circle opens a little behind in the direction of the 
mouth. The arms are each composed of three articulations, the 
first or lowest being much the longest, the last the shortest ; 
they are all furnished with afew hairs on the margins and extre- 
mities : the four arms next the mouth have attached to their m- 
ner margins at the junction of the first and second articulations 
an oval cushion-like body (Pl. VIII. fig. 9, and Pl. IX. fig. 1 6) 
placed longitudinally, and wrinkled transversely, most probably 
for thé purpose of prehension. Immediately behind the arms pro- 
jects a large conical body (Pl. VIII. fig. 6 f and fig. 7 a) con- 
taining the mouth (fig. 6 e & fig. 7 ), which is placed near the 
base in front towards the circle of arms. The greater portion of 
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