Fam. 1, Plate 21 a. 



THECACERA PENNIGERA, Montagu, sp. 



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T. albida, aurantiaco nigroque maculata ; vaginis tentaculorum patulis, lobatis ; branchiis 3 tri- 

 pinnatis ; appendicibus branchialibus, 1 utrinque, clavatis ; angulis anterioribus pedis productis. 



Doris penniyera, Mont, in Linn. Trans., v. 11, p. 17, pi. 4, fig. 5. 

 Thecacera penniyera, Flem. Brit. Anim., 283. 



Forbes and Hanley, Brit. Moll., v. 3, p. 575. 



Hab. Rocks 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 com- 

 mon 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 

 branchias, 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 



