_Genera_--CREUSIA AND CHELONOBIA.
Fig. 6 _i_, 6 _k_, 6 _l_, Creusia spinulosa, _var._ 4, 6 _i_,
tergum, external view; 6 _k_, the same, from another
individual; 6 _l_, the same, internal view.
6 _m_, Creusia spinulosa, _var._ 5, tergum, external view.
6 _n_, 6_o_, 6_p_, 6_q_, Creusia spinulosa, _var._ 6, 6 _n_,
scutum, external view of; 6 _o_, tergum of same individual,
external view of; 6 _p_, scutum of another individual,
external view of; 6 _q_, tergum of latter, external view of.
6 _r_, Creusia spinulosa, _var._ 7, scutum, internal view of.
6 _s_, Creusia spinulosa, _var._ 9, scutum and tergum,
calcified together, external view.
6 _t_, Creusia spinulosa, _var._ 10, scutum and tergum,
calcified together, external view.
6 _U_, Creusia spinulosa, _var._ 11, shell seen from above; 6
_u_, scutum and tergum, calcified together, external view.
Fig. 1 _a_, Chelonobia testudinaria, shell seen from above; a
specimen has been chosen, with some of the radii smooth,
and others more or less notched; 1 _b_, scutum, internal
view of; 1 _c_, tergum, internal view of; 1 _d_, scutum and
tergum, joined together, external view of.
2, Chelonobia caretta, shell seen from above.
3 _a_, Chelonobia patula, shell seen from above; 3 _b_,
tergum, external view of.
4, Carina of Chelonobia patula, seen from within; _a a_, outer
lamina of wall, joined by the longitudinal septa to _b_,
the inner lamina; _e c e_, sheath, descending to the base
of shell, with the middle part largely hollowed out; the
upper part of the sheath, above _d d_, is transversely
marked by the lines of attachment of the opercular
membrane; _d_, _d_, alæ.
5, View of the edge of the radius of the rostrum of Chelonobia
testudinaria.
_a_, _a_, inner portion of radius.
_b_, thick outer lamina of the radius, transversely pitted;
beneath this pitted portion, which forms only the outer
surface of the radius, and distinct from the inner portion
_a_, the arborescent and dentated sutural edges of this
outer lamina are seen.
_c_, outer lamina of wall of compartment.
_d_, the exterior septum, connecting the outer lamina of
the wall to the inner lamina; the basal edge of the inner
lamina of the wall is seen beneath and without the lower
end of the inner portion (_a_) of the radius.