Fam. 1, Plate 21 a.
THECACERA PENNIGERA, Montagu, sp.
T. albida, aurantiaco nigroque maculata; vaginis tentaculorum patulis, lobatis j braucbiis 3 tri-
pinnatis; appendicibus branchialibus, 1 utrinque, clavatis ; angulis anterioribus pedis productis.
Doris pennigera, Mont, in Linn. Trans., v. 11, p. 17, pi. 4, fig. 5.
Thecacera pennigera, Flem. Brit. Anim., 283.
Forbes and Hanley, Brit. Moll., v. 3, p. 575.
Hab. Bocks at low-water mark, Milton, Devonshire, Montagu. Cornwall, R. Q. Couch, Esq.
Weymouth, W. Thompson, Esq.
Body half an inch long, nearly linear, much rounded above, and tapering to a point
behind; transparent white, tinged with yellow from the viscera appearing through, and
covered with irregular bright orange blotches and spots, interspersed with smaller spots of
velvety black, slightly inclining to puce-colour; these latter are pretty evenly circular, with
granulated margins, which, in Montagu’s specimens, assumed a radiated appearance under a
lens. Tentacles rather stout, linear, laminated with about fourteen plates, terminating in a
narrow ridge in front; yellow, with black spots. They issue from wide sheaths, forming an
expansion on the outside of each tentacle, which it encircles for nearly two thirds of
the circumference, terminating abruptly towards the inside. The margin is plain, rising into
a strong, blunt process behind; the anterior side is very slightly elevated. Head narrow,
without oral tentacles or distinct veil, and slightly notched in front from an extension of the
groove formed by the buccal aperture. Branchial plumes three, tripinnate, rising from a common
footstalk near the middle of the back. They are transparent white, with orange and black
blotches and spots. Branchial appendages one on each side, set at a little distance behind the
branchiae, linear or subclavate, rounded at the top, blotched and spotted with orange and
black (in Montagu’s specimen they were bifid, but this is most likely an accidental variety).
Foot linear, very narrow, transparent white, strongly grooved in front, and notched on the
upper lamina ; the angles produced into sharp tentacular points at the sides.
Spicula robust, linear, with the extremities pointed and bent in the same direction,
irregularly nodulous ; the nodules larger in the centre, and towards the extremities. Their
form, however, varies considerably; some are regularly arched in the centre, with the ends
truncate, others are almost straight; some again have their extremities furnished with two or
more obtuse points, while specimens occur much angulated and irregularly bent in the centre,
with the ends rounded, enlarged, and recurved.
Having for several years sought for this interesting species in vain, we had despaired of
being able to give figures of it, when Mr. Wm. Thompson, of Weymouth, had the good fortune
to meet with it at that place, and kindly sent us a living specimen. We are thus enabled to