Polyceka. MOLLUSCA. BRANCHIFERA. 283 



136. D. quadricornis. — Cloak smooth in the middle, with a 

 row of obsolete tubercles on each side ; tentacula approximat- 

 ing in pairs. 



Mont. Linn. Trans, xi. 17- 1. iv. f. 4. — Coast of Devon. 

 Length |ths of an inch, mottled with brown and white ; tentacula long, 

 slender ; branchial plumes about 8 in number. 



137. D. nigricans. — Cloak thickly covered with short lan- 

 ceolate tubercles ; branchial plumes about 8 in number. 



Flem. Edin. Encyc. vol. xiv. p. 618 — Zetland. 

 Length about half an inch, pale, freckled with dusky ; cloak emarginate 

 anteally ; sheath of the superior tentacula notched in the margin. 



Gen. XXXVI. POLYCERA.— Oral, tentacula exceeding 

 two in number ; branchiae, when at rest covered, by two 

 scales. 



138. Y.flava. — Oral, tentacula four ; superior tentacula awl 

 shaped ; branchial scales smooth, produced. 



Doris flava, Mont. Linn. Trans, vii. 79- t. vii. f. 6 — Coast of Devon. 

 Length upwards of half an inch, narrow behind ; body spotted with bright 

 orange yellow ; branchial plumes 7 in number, behind which are the long 

 scales or fleshy appendages. 



139- P- pennigera. — Upper tentacula subclavate, perfoliate, 

 with a bifid basilar sheath. 



Doris penn. Mont. Linn. Trans, xi. 17- t. iv. f. 5. — Devon coast, rare. 



Length an inch ; bifid anteally, acuminated behind ; spotted with orange 

 and black ; branchial plumes 5, with two bifid appendages.— .The absence of 

 the oral tentacula, and the peculiar character of the superior ones, and of the 

 branchial appendage, mark this species as the type of a new genus, which may 

 be termed Thecacera. 



In 1814 I observed an animal in a pool among the rocks on the shore near 

 Aberbrothock, Angus-shire, which probably belonged to the genus Polycera, 

 but which I was unable to secure. The oral tentacula were 6 in number ; 

 the superior tentacula produced, and beautifully pinnate ; the branchial plumes 

 were numerous ; body wide before, becoming very narrow behind the vent. 



Gen. XXXVII. TERGIPES— Branchise, furnished witli 

 a sheath at the base, in a single row on each side, and ca- 

 pable of acting as suckers., 



• 140. T. maculatus. — Branchia?, 4 on each side and 1 near 

 the extremity of the body, consisting of a clavate sheath with 

 a sexpartite margin, and a concave summit with a central pa- 

 pilla. 



Doris maculata, Mcnt. Linn. Trans, vii. 80. t. vii. f. 8, 9.— Coast of 

 Devon. 



