88 
CRUSTACEA—CIRRIPEDIA 
CHAP, 
of them, e.g. Oxynaspis, live at considerable depths attached to 
Fie. 57.—Conchoderma  vir- 
gata, x 1. C, Carina; 
S, scutum; 7, tergum. 
(After Darwin.) 
corals, ete., but large numbers float on the 
surface of the sea, fixed often on logs and 
wreckage of various kinds.  Dichelaspis 
is found attached to the shells of large 
Crustacea. 
Conchoderma is an interesting genus, 
the species of which live affixed to various 
floating objects, the keels of ships, ete. ; 
the mantle is often brilliantly coloured, 
as in C. virgata, and the skeletal plates 
are reduced to the merest vestiges, leaving 
the greater part of the body fleshy. 
Fam. 3. Tetraspidae.—This family 
includes the single genus Jbla (Fig. 58), 
which possesses only four skeletal plates, 
a pair of terga and of scuta, coloured 
blue, while the peduncle is covered with 
brown spines. There are only two very 
similar species known, J. cwming?i, which is found attached to the 
peduncle of Pollicipes 
mitella, and L. qua- 
drivalvis, living on 
masses of the Siph- 
onophore  Galeolaria 
decumbens. These two 
species are quite differ- 
ent in the partition 
liciae se 
cumingit the large 
individuals of normal 
structure are females, 
inside the mantle- 
cavities of which are 
attached dwarf males 
of the form shown in 
Fig. 59. 
of the sexes. 
Fic. 58.—Ibla cumingii, 
?, x l. 8S, Seutum ; 
T, tergum. (After 
Darwin.) 
These organisms 
have the peduncle 
buried completely in the substance of the 
Fia. 59.— lbla cumingii, wart 
male, x 32. A, Antennae ; 
B, part of male imbedded 
in the female, to which the 
torn membrane M belongs ; 
EE, eye; Th, thoracic ap- 
pendages or cirri, (After 
Darwin.) 
female’s mantle, inside 
