o question that the scuta of the female are specially modified
by their own growth for the reception of the males. It must be added
that, as it was not possible to ascertain whether the ordinary form of
_S. rutilum_ was hermaphrodite or female, so it must remain doubtful
whether the parasites are males or complemental males; but the former, I
think, is most probable.

[=TT= SUB-CARINA PRESENTE.]

4. SCALPELLUM ROSTRATUM. Pl. VI, fig. 7.

_S. (Herm.) valvis 15: rostro permagno: laterum paribus quatuor: pari
superiore pentagono._

(Herm.) Capitulum with 15 valves: rostrum very large: four pair of
latera; upper latera pentagonal.

Mandibles with four teeth; maxillae with the inferior angle prominent.

_Complemental Male_, attached between the mouth and adductor scutorum
muscle; pedunculated; capitulum bearing a pair of elongated scuta and a
rudimentary carina; mouth and cirri prehensile.

Philippine Archipelago; Island of Bantayan. Attached to a horny
coralline: 20 fathoms. Mus. Cuming.

HERMAPHRODITE.

_Capitulum_, with the upper part narrow and produced.

_Valves_, 15 in number, placed close together, clouded pale red, covered
with membrane, which is thickly clothed with minute points.

_Scuta_ rather small, oval, with the upper end pointed; rather convex;
basal and lateral margins blending into each other; the upper produced
portion above the umbo is small; there is a deep pit for the adductor
muscle, and there is a fold on the occludent margin in the usual
position; occludent margin not straight.

_Terga_ large, one third of their own length longer than the scuta; fat,
sub-triangular; the three margins are not quite straight; the carinal
margin projects a little above the apex of the carina, and the scutal
margin is excised to fit the upper part of the scuta.

_Carina_ bowed, internally deeply concave; upper portion above the umbo,
about one fourth of the total length, extending between the terga for
two thirds of their length, up to the slight prominences on their
carinal margins: a ridge separates, on each side, the parietes from the
tectum.

_Rostrum_ (fig. 7 _a_) unusually large, about two thirds of the length
of the scuta, and twice as long as the rostral pair of latera;
internally concave, externally carinated; outline of the upper portion
acutely triangular, of the lower portion rounded; umbo seated at the
upper end.

_Upper Latera_ pentagonal, with the apex rounded.

_Rostral La